CMP Journal 2025-02-05
Statistics
Nature: 31
Nature Materials: 1
Physical Review Letters: 14
Physical Review X: 2
arXiv: 57
Nature
Superfluid stiffness of twisted trilayer graphene superconductors
Original Paper | Electronic properties and materials | 2025-02-04 19:00 EST
Abhishek Banerjee, Zeyu Hao, Mary Kreidel, Patrick Ledwith, Isabelle Phinney, Jeong Min Park, Andrew Zimmerman, Marie E. Wesson, Kenji Watanabe, Takashi Taniguchi, Robert M. Westervelt, Amir Yacoby, Pablo Jarillo-Herrero, Pavel A. Volkov, Ashvin Vishwanath, Kin Chung Fong, Philip Kim
The robustness of the macroscopic quantum nature of a superconductor can be characterized by the superfluid stiffness, ρs, a quantity that describes the energy required to vary the phase of the macroscopic quantum wavefunction. In unconventional superconductors, such as cuprates, the low-temperature behaviour of ρs markedly differs from that of conventional superconductors owing to quasiparticle excitations from gapless points (nodes) in momentum space. Intensive research on the recently discovered magic-angle twisted graphene family has revealed, in addition to superconducting states, strongly correlated electronic states associated with spontaneously broken symmetries, inviting the study of ρs to uncover the potentially unconventional nature of its superconductivity. Here we report the measurement of ρs in magic-angle twisted trilayer graphene (TTG), revealing unconventional nodal-gap superconductivity. Utilizing radio-frequency reflectometry techniques to measure the kinetic inductive response of superconducting TTG coupled to a microwave resonator, we find a linear temperature dependence of ρs at low temperatures and nonlinear Meissner effects in the current-bias dependence, both indicating nodal structures in the superconducting order parameter. Furthermore, the doping dependence shows a linear correlation between the zero-temperature ρs and the superconducting transition temperature Tc, reminiscent of Uemura's relation in cuprates, suggesting phase-coherence-limited superconductivity. Our results provide strong evidence for nodal superconductivity in TTG and put strong constraints on the mechanisms of these graphene-based superconductors.
Electronic properties and materials, Superconducting properties and materials
The genetic origin of the Indo-Europeans
Original Paper | Archaeology | 2025-02-04 19:00 EST
Iosif Lazaridis, Nick Patterson, David Anthony, Leonid Vyazov, Romain Fournier, Harald Ringbauer, Iñigo Olalde, Alexander A. Khokhlov, Egor P. Kitov, Natalia I. Shishlina, Sorin C. Ailincăi, Danila S. Agapov, Sergey A. Agapov, Elena Batieva, Baitanayev Bauyrzhan, Zsolt Bereczki, Alexandra Buzhilova, Piya Changmai, Andrey A. Chizhevsky, Ion Ciobanu, Mihai Constantinescu, Marietta Csányi, János Dani, Peter K. Dashkovskiy, Sándor Évinger, Anatoly Faifert, Pavel Flegontov, Alin Frînculeasa, Mădălina N. Frînculeasa, Tamás Hajdu, Tom Higham, Paweł Jarosz, Pavol Jelínek, Valeri I. Khartanovich, Eduard N. Kirginekov, Viktória Kiss, Alexandera Kitova, Alexeiy V. Kiyashko, Jovan Koledin, Arkady Korolev, Pavel Kosintsev, Gabriella Kulcsár, Pavel Kuznetsov, Rabadan Magomedov, Aslan M. Mamedov, Eszter Melis, Vyacheslav Moiseyev, Erika Molnár, Janet Monge, Octav Negrea, Nadezhda A. Nikolaeva, Mario Novak, Maria Ochir-Goryaeva, György Pálfi, Sergiu Popovici, Marina P. Rykun, Tatyana M. Savenkova, Vladimir P. Semibratov, Nikolai N. Seregin, Alena Šefčáková, Raikhan S. Mussayeva, Irina Shingiray, Vladimir N. Shirokov, Angela Simalcsik, Kendra Sirak, Konstantin N. Solodovnikov, Judit Tárnoki, Alexey A. Tishkin, Viktor Trifonov, Sergey Vasilyev, Ali Akbari, Esther S. Brielle, Kim Callan, Francesca Candilio, Olivia Cheronet, Elizabeth Curtis, Olga Flegontova, Lora Iliev, Aisling Kearns, Denise Keating, Ann Marie Lawson, Matthew Mah, Adam Micco, Megan Michel, Jonas Oppenheimer, Lijun Qiu, J. Noah Workman, Fatma Zalzala, Anna Szécsényi-Nagy, Pier Francesco Palamara, Swapan Mallick, Nadin Rohland, Ron Pinhasi, David Reich
The Yamnaya archaeological complex appeared around 3300 bc across the steppes north of the Black and Caspian Seas, and by 3000 bc it reached its maximal extent, ranging from Hungary in the west to Kazakhstan in the east. To localize Yamnaya origins among the preceding Eneolithic people, we assembled ancient DNA from 435 individuals, demonstrating three genetic clines. A Caucasus-lower Volga (CLV) cline suffused with Caucasus hunter-gatherer1 ancestry extended between a Caucasus Neolithic southern end and a northern end at Berezhnovka along the lower Volga river. Bidirectional gene flow created intermediate populations, such as the north Caucasus Maikop people, and those at Remontnoye on the steppe. The Volga cline was formed as CLV people mixed with upriver populations of Eastern hunter-gatherer2 ancestry, creating hypervariable groups, including one at Khvalynsk. The Dnipro cline was formed when CLV people moved west, mixing with people with Ukraine Neolithic hunter-gatherer ancestry3 along the Dnipro and Don rivers to establish Serednii Stih groups, from whom Yamnaya ancestors formed around 4000 bc and grew rapidly after 3750-3350 bc. The CLV people contributed around four-fifths of the ancestry of the Yamnaya and, entering Anatolia, probably from the east, at least one-tenth of the ancestry of Bronze Age central Anatolians, who spoke Hittite4,5. We therefore propose that the final unity of the speakers of ‘proto-Indo-Anatolian', the language ancestral to both Anatolian and Indo-European people, occurred in CLV people some time between 4400 bc and 4000 bc.
Archaeology, Evolutionary biology, Evolutionary genetics, Population genetics
Directly imaging the cooling flow in the Phoenix cluster
Original Paper | Astrophysical plasmas | 2025-02-04 19:00 EST
Michael Reefe, Michael McDonald, Marios Chatzikos, Jerome Seebeck, Richard Mushotzky, Sylvain Veilleux, Steven W. Allen, Matthew Bayliss, Michael Calzadilla, Rebecca Canning, Benjamin Floyd, Massimo Gaspari, Julie Hlavacek-Larrondo, Brian McNamara, Helen Russell, Keren Sharon, Taweewat Somboonpanyakul
In the centres of many galaxy clusters, the hot (approximately 107 kelvin) intracluster medium can become dense enough that it should cool on short timescales1,2. However, the low measured star formation rates in massive central galaxies3,4,5,6 and the absence of soft X-ray lines from the cooling gas7,8,9 suggest that most of this gas never cools. This is known as the cooling flow problem. The latest observations suggest that black hole jets are maintaining the vast majority of gas at high temperatures10,11,12,13,14,15,16. A cooling flow has yet to be fully mapped through all the gas phases in any galaxy cluster. Here we present observations of the Phoenix cluster17 using the James Webb Space Telescope to map the [Ne vi] λ 7.652-μm emission line, enabling us to probe the gas at 105.5 kelvin on large scales. These data show extended [Ne vi] emission that is cospatial with the cooling peak in the intracluster medium, the coolest gas phases and the sites of active star formation. Taken together, these imply a recent episode of rapid cooling, causing a short-lived spike in the cooling rate, which we estimate to be 5,000-23,000 solar masses per year. These data provide a large-scale map of gas at temperatures between 105 kelvin and 106 kelvin in a cluster core, and highlight the critical role that black hole feedback has in not only regulating cooling but also promoting it18.
Astrophysical plasmas, Galaxies and clusters, High-energy astrophysics
Distributed quantum computing across an optical network link
Original Paper | Quantum information | 2025-02-04 19:00 EST
D. Main, P. Drmota, D. P. Nadlinger, E. M. Ainley, A. Agrawal, B. C. Nichol, R. Srinivas, G. Araneda, D. M. Lucas
Distributed quantum computing (DQC) combines the computing power of multiple networked quantum processing modules, ideally enabling the execution of large quantum circuits without compromising performance or qubit connectivity1,2. Photonic networks are well suited as a versatile and reconfigurable interconnect layer for DQC; remote entanglement shared between matter qubits across the network enables all-to-all logical connectivity through quantum gate teleportation (QGT)3,4. For a scalable DQC architecture, the QGT implementation must be deterministic and repeatable; until now, no demonstration has satisfied these requirements. Here we experimentally demonstrate the distribution of quantum computations between two photonically interconnected trapped-ion modules. The modules, separated by about two metres, each contain dedicated network and circuit qubits. By using heralded remote entanglement between the network qubits, we deterministically teleport a controlled-Z (CZ) gate between two circuit qubits in separate modules, achieving 86% fidelity. We then execute Grover's search algorithm5--to our knowledge, the first implementation of a distributed quantum algorithm comprising several non-local two-qubit gates--and measure a 71% success rate. Furthermore, we implement distributed iSWAP and SWAP circuits, compiled with two and three instances of QGT, respectively, demonstrating the ability to distribute arbitrary two-qubit operations6. As photons can be interfaced with a variety of systems, the versatile DQC architecture demonstrated here provides a viable pathway towards large-scale quantum computing for a range of physical platforms.
Quantum information, Quantum mechanics
Cretaceous Antarctic bird skull elucidates early avian ecological diversity
Original Paper | Palaeontology | 2025-02-04 19:00 EST
Christopher R. Torres, Julia A. Clarke, Joseph R. Groenke, Matthew C. Lamanna, Ross D. E. MacPhee, Grace M. Musser, Eric M. Roberts, Patrick M. O'Connor
Fossils representing Cretaceous lineages of crown clade birds (Aves) are exceptionally rare but are crucial to elucidating major ecological shifts across early avian divergences. Among the earliest known putative crown birds is Vegavis iaai1,2,3,4,5, a foot-propelled diver from the latest Cretaceous (69.2-68.4 million years ago)6 of Antarctica with controversial phylogenetic affinities2,7,8,9,10. Initially recovered by phylogenetic analyses as a stem anatid (ducks and closely related species)1,2,11, Vegavis has since been recovered as a stem member of Anseriformes (waterfowl)7,8,9, or outside Aves altogether10. Here we report a new, nearly complete skull of Vegavis that provides new insight into its feeding ecology and exhibits morphologies that support placement among waterfowl within crown-group birds. Vegavis has an avian beak (absence of teeth and reduced maxilla) and brain shape (hyperinflated cerebrum and ventrally shifted optic lobes). The temporal fossa is well excavated and expansive, indicating that this bird had hypertrophied jaw musculature. The beak is narrow and pointed, and the mandible lacks retroarticular processes. Together, these features comprise a feeding apparatus unlike that of any other known anseriform but like that of other extant birds that capture prey underwater (for example, grebes and loons). The Cretaceous occurrence of Vegavis, with a feeding ecology unique among known Galloanserae (waterfowl and landfowl), is further indication that the earliest anseriform divergences were marked by evolutionary experiments unrepresented in the extant diversity3,11,12,13.
Palaeontology, Phylogenetics
Metal-halide porous framework superlattices
Original Paper | Metal-organic frameworks | 2025-02-04 19:00 EST
Wenqiang Zhang, Hong Jiang, Yikuan Liu, Yue Hu, Athulya Surendran Palakkal, Yujie Zhou, Meng Sun, Enping Du, Wei Gong, Qun Zhang, Jianwen Jiang, Jinqiao Dong, Yan Liu, Dehui Li, Yihan Zhu, Yong Cui, Xiangfeng Duan
The construction of superlattices with a spatial modulation of chemical compositions allows for the creation of artificial materials with tailorable periodic potential landscapes and tunable electronic and optical properties<a data-test="citation-ref" data-track="click" data-track-action="reference anchor" data-track-label="link" href="https://www.nature.com/articles/s41586-024-08447-0#ref-CR1" id="ref-link-section-d22240765e620" title="Esaki, L. & Chang, L. L. New transport phenomenon in a semiconductor "superlattice". Phys. Rev. Lett. 33, 495-498 (1974).">1,2,3,4,5. Conventional semiconductor superlattices with designable potential modulation in one dimension has enabled high-electron-mobility transistors and quantum-cascade lasers. More recently, a diverse set of superlattices has been constructed through self-assembly or guided assembly of multiscale building units, including zero-dimensional nanoclusters and nanoparticles6,7, one-dimensional nanorods and nanowires8,9, two-dimensional nanolayers and nanosheets10,11,12,13, and hybrid two-dimensional molecular assemblies14,15,16,17. These self-assembled superlattices feature periodic structural modulation in two or three dimensions, but often lack atomic precision owing to the inevitable structural disorder at the interfaces between the constituent units. Here we report a one-pot synthesis of multi-dimensional single-crystalline superlattices consisting of periodic arrangement of zero-, one- and two-dimensional building units. By exploiting zirconium (IV) metal-organic frameworks as host templates for directed nucleation and precise growth of metal-halide sublattices through a coordination-assisted assembly strategy, we synthesize a family of single-crystalline porous superlattices. Single-crystal X-ray crystallography and high-resolution transmission electron microscopy clearly resolve the high-order superlattice structure with deterministic atomic coordinates. Further treatment with selected amine molecules produces perovskite-like superlattices with highly tunable photoluminescence and chiroptical properties. Our study creates a platform of high-order single-crystalline porous superlattices, opening opportunities to tailor the electronic, optical and quantum properties beyond the reach of conventional crystalline solids.
Metal-organic frameworks, Molecular self-assembly, Solid-state chemistry
IL-27 elicits a cytotoxic CD8+ T cell program to enforce tumour control
Original Paper | Cytotoxic T cells | 2025-02-04 19:00 EST
Béatrice Bréart, Katherine Williams, Stellanie Krimm, Tiffany Wong, Brandon D. Kayser, Lifen Wang, Eric Cheng, Mayra Cruz Tleugabulova, Romain Bouziat, Tianshi Lu, Kobe Yuen, Natalie S. Firmino, Daniel D. Bravo, Juliette Roels, Atish Bhakta, Jack Bevers 3rd, Isabelle Lehoux, Alan Gutierrez, Yajun Chestnut, Joanna E. Klementowicz, Teresita L. Arenzana, Ilseyar Akhmetzyanova, Elizabeth Dixon, Min Chen, Kazi Tasneem, Rajbharan Yadav, Hartmut Koeppen, Soyoung A. Oh, Lélia Delamarre, Haochu Huang, Shion A. Lim, Gerald Nakamura, Jianyong Wang, Chan Gao, Racquel Corpuz, Sören Müller, Nathaniel R. West
Although cytotoxic CD8+ T lymphocytes (CTLs) are essential for anti-tumour immunity, they are frequently dysfunctional in tumours1. Cytokines that sustain CTL activity are attractive for cancer immunotherapy, but avoiding inflammatory toxicity remains a challenge for their clinical use2. Here we show that expression of a CTL signature is strongly associated with IL27 expression in human and mouse tumours. In mice, IL-27 acts directly on tumour-specific CTLs to promote their persistence and effector function in the tumour microenvironment. Moreover, treatment with inducible IL-27 overexpression or a half-life-extended IL-27 protein in vivo is well tolerated, induces regression of established tumours, drives an enhanced cytotoxic program in anti-tumour CTLs and synergizes with PD-L1 blockade. In patients with cancer who were treated with anti-PD-1/PD-L1 therapy, high expression of IL-27 correlates with a favourable clinical response, and IL-27 supports human CTL function during chronic antigen stimulation ex vivo. Our data demonstrate that endogenous IL-27 is essential for anti-tumour immunity and that IL-27 receptor agonism can safely improve anti-tumour T cell responses alone or in combination with PD-L1 blockade.
Cytotoxic T cells, Interleukins, Tumour immunology
Superfluid stiffness of magic-angle twisted bilayer graphene
Original Paper | Electronic properties and devices | 2025-02-04 19:00 EST
Miuko Tanaka, Joel Î-j. Wang, Thao H. Dinh, Daniel Rodan-Legrain, Sameia Zaman, Max Hays, Aziza Almanakly, Bharath Kannan, David K. Kim, Bethany M. Niedzielski, Kyle Serniak, Mollie E. Schwartz, Kenji Watanabe, Takashi Taniguchi, Terry P. Orlando, Simon Gustavsson, Jeffrey A. Grover, Pablo Jarillo-Herrero, William D. Oliver
The physics of superconductivity in magic-angle twisted bilayer graphene (MATBG) is a topic of keen interest in moiré systems research, and it may provide an insight into the pairing mechanism of other strongly correlated materials such as high-critical-temperature superconductors. Here we use d.c. transport and microwave circuit quantum electrodynamics to directly measure the superfluid stiffness of superconducting MATBG through its kinetic inductance. We find the superfluid stiffness to be much larger than expected from conventional Fermi liquid theory. Rather, it is comparable to theoretical predictions1 and recent experimental indications2 of quantum geometric effects that are dominant at the magic angle. The temperature dependence of the superfluid stiffness follows a power law, which contraindicates an isotropic Bardeen-Cooper-Schrieffer (BCS) model. Instead, the extracted power-law exponents indicate an anisotropic superconducting gap, whether interpreted in the Fermi liquid framework or by considering the quantum geometry of flat-band superconductivity. Moreover, a quadratic dependence of the superfluid stiffness on both d.c. and microwave current is observed, which is consistent with the Ginzburg-Landau theory. Taken together, our findings show that MATBG is an unconventional superconductor with an anisotropic gap and strongly suggest a connection between quantum geometry, superfluid stiffness and unconventional superconductivity in MATBG. The combined d.c.-microwave measurement platform used here is applicable to the investigation of other atomically thin superconductors.
Electronic properties and devices, Superconducting properties and materials
Fungal impacts on Earth's ecosystems
Review Paper | Ecological networks | 2025-02-04 19:00 EST
Nicola T. Case, Sarah J. Gurr, Matthew C. Fisher, David S. Blehert, Charles Boone, Arturo Casadevall, Anuradha Chowdhary, Christina A. Cuomo, Cameron R. Currie, David W. Denning, Iuliana V. Ene, Lillian K. Fritz-Laylin, Aleeza C. Gerstein, Neil A. R. Gow, Asiya Gusa, Iliyan D. Iliev, Timothy Y. James, Hailing Jin, Regine Kahmann, Bruce S. Klein, James W. Kronstad, Kyla S. Ost, Kabir G. Peay, Rebecca S. Shapiro, Donald C. Sheppard, Neta Shlezinger, Jason E. Stajich, Eva H. Stukenbrock, John W. Taylor, Gerard D. Wright, Leah E. Cowen, Joseph Heitman, Julia A. Segre
Over the past billion years, the fungal kingdom has diversified to more than two million species, with over 95% still undescribed. Beyond the well-known macroscopic mushrooms and microscopic yeast, fungi are heterotrophs that feed on almost any organic carbon, recycling nutrients through the decay of dead plants and animals and sequestering carbon into Earth's ecosystems. Human-directed applications of fungi extend from leavened bread, alcoholic beverages and biofuels to pharmaceuticals, including antibiotics and psychoactive compounds. Conversely, fungal infections pose risks to ecosystems ranging from crops to wildlife to humans; these risks are driven, in part, by human and animal movement, and might be accelerating with climate change. Genomic surveys are expanding our knowledge of the true biodiversity of the fungal kingdom, and genome-editing tools make it possible to imagine harnessing these organisms to fuel the bioeconomy. Here, we examine the fungal threats facing civilization and investigate opportunities to use fungi to combat these threats.
Ecological networks, Fungal biology
Engineering a genomically recoded organism with one stop codon
Original Paper | Genomic engineering | 2025-02-04 19:00 EST
Michael W. Grome, Michael T. A. Nguyen, Daniel W. Moonan, Kyle Mohler, Kebron Gurara, Shenqi Wang, Colin Hemez, Benjamin J. Stenton, Yunteng Cao, Felix Radford, Maya Kornaj, Jaymin Patel, Maisha Prome, Svetlana Rogulina, David Sozanski, Jesse Tordoff, Jesse Rinehart, Farren J. Isaacs
The genetic code is conserved across all domains of life, yet exceptions have revealed variations in codon assignments and associated translation factors1,2,3. Inspired by this natural malleability, synthetic approaches have demonstrated whole-genome replacement of synonymous codons to construct genomically recoded organisms (GROs)4,5 with alternative genetic codes. However, no efforts have fully leveraged translation factor plasticity and codon degeneracy to compress translation function to a single codon and assess the possibility of a non-degenerate code. Here we describe construction and characterization of Ochre, a GRO that fully compresses a translational function into a single codon. We replaced 1,195 TGA stop codons with the synonymous TAA in ∆TAG Escherichia coli C321.∆A4. We then engineered release factor 2 (RF2) and tRNATrp to mitigate native UGA recognition, translationally isolating four codons for non-degenerate functions. Ochre thus utilizes UAA as the sole stop codon, with UGG encoding tryptophan and UAG and UGA reassigned for multi-site incorporation of two distinct non-standard amino acids into single proteins with more than 99% accuracy. Ochre fully compresses degenerate stop codons into a single codon and represents an important step toward a 64-codon non-degenerate code that will enable precise production of multi-functional synthetic proteins with unnatural encoded chemistries and broad utility in biotechnology and biotherapeutics.
Genomic engineering, Synthetic biology, tRNAs
Limited impact of Salmonella stress and persisters on antibiotic clearance
Original Paper | Antibiotics | 2025-02-04 19:00 EST
Joseph Fanous, Beatrice Claudi, Vishwachi Tripathi, Jiagui Li, Frédéric Goormaghtigh, Dirk Bumann
Antimicrobial compounds are essential for controlling bacterial infections. Stress-induced bacterial tolerance and persisters can undermine antimicrobial activities under laboratory conditions, but their quantitative effects under physiological conditions remain unclear1,2. Here we determined constraints on clearance of Salmonella by antimicrobials in infected mice and tissue-mimicking chemostats. The antibiotics enrofloxacin and ceftriaxone exhibited poor anti-Salmonella activity under both conditions, primarily owing to severe nutrient starvation, which restricted Salmonella replication3,4,5. Other infection-associated conditions, such as acidic pH, glucose, oxidative stress, nitrosative stress, antimicrobial peptides, osmolarity, oxygen limitation, carbon dioxide and carbonate, as well as drug efflux, toxin-antitoxin modules and cell size had limited effects. A subset of resilient Salmonella appeared as a key obstacle for clearance by enrofloxacin, based on the biphasic decline of Salmonella colony-forming units. However, these data were misleading, because colony formation was confounded by extensive post-exposure killing. More accurate single-cell, real-time assays showed uniformly slow damage, indicating high resilience across the entire Salmonella population. The resulting extensive survival of bulk bacteria minimized the effect of hyper-resilient persisters. Thus, starvation-induced general resilience of Salmonella was the main cause of poor antibiotic clearance. These findings highlight the importance of quantifying antibiotic activity with real-time, single-cell assays under physiological conditions.
Antibiotics, Pathogens
Synthetic lethality of mRNA quality control complexes in cancer
Original Paper | Cancer | 2025-02-04 19:00 EST
Vivian Prindle, Adam E. Richardson, Kimberly R. Sher, Sarah Kongpachith, Kaitlin Kentala, Sakina Petiwala, Dong Cheng, Deborah Widomski, Phuong Le, Maricel Torrent, Anlu Chen, Stephen Walker, Marianne B. Palczewski, Diya Mitra, Vlasios Manaves, Xu Shi, Charles Lu, Stephanie Sandoval, Zoltan Dezso, F. Gregory Buchanan, Daniel Verduzco, Brian Bierie, Jonathan A. Meulbroek, William N. Pappano, Joshua P. Plotnik
Synthetic lethality exploits the genetic vulnerabilities of cancer cells to enable a targeted, precision approach to treat cancer1. Over the past 15 years, synthetic lethal cancer target discovery approaches have led to clinical successes of PARP inhibitors2 and ushered several next-generation therapeutic targets such as WRN3, USP14, PKMYT15, POLQ6 and PRMT57 into the clinic. Here we identify, in human cancer, a novel synthetic lethal interaction between the PELO-HBS1L and SKI complexes of the mRNA quality control pathway. In distinct genetic contexts, including 9p21.3-deleted and high microsatellite instability (MSI-H) tumours, we found that phenotypically destabilized SKI complex leads to dependence on the PELO-HBS1L ribosomal rescue complex. PELO-HBS1L and SKI complex synthetic lethality alters the normal cell cycle and drives the unfolded protein response through the activation of IRE1, as well as robust tumour growth inhibition. Our results indicate that PELO and HBS1L represent novel therapeutic targets whose dependence converges upon SKI complex destabilization, a common phenotypic biomarker in diverse genetic contexts representing a significant population of patients with cancer.
Cancer, Target identification, Target validation, Tumour biomarkers, Tumour-suppressor proteins
Quantum coarsening and collective dynamics on a programmable simulator
Original Paper | Phase transitions and critical phenomena | 2025-02-04 19:00 EST
Tom Manovitz, Sophie H. Li, Sepehr Ebadi, Rhine Samajdar, Alexandra A. Geim, Simon J. Evered, Dolev Bluvstein, Hengyun Zhou, Nazli Ugur Koyluoglu, Johannes Feldmeier, Pavel E. Dolgirev, Nishad Maskara, Marcin Kalinowski, Subir Sachdev, David A. Huse, Markus Greiner, Vladan Vuletić, Mikhail D. Lukin
Understanding the collective quantum dynamics of non-equilibrium many-body systems is an outstanding challenge in quantum science. In particular, dynamics driven by quantum fluctuations are important for the formation of exotic quantum phases of matter1, fundamental high-energy processes2, quantum metrology3,4 and quantum algorithms5. Here we use a programmable quantum simulator based on Rydberg atom arrays to experimentally study collective dynamics across a (2+1)-dimensional Ising quantum phase transition. After crossing the quantum critical point, we observe a gradual growth of correlations through coarsening of antiferromagnetically ordered domains6. By deterministically preparing and following the evolution of ordered domains, we show that the coarsening is driven by the curvature of domain boundaries, and find that the dynamics accelerate with proximity to the quantum critical point. We quantitatively explore these phenomena and further observe long-lived oscillations of the order parameter, corresponding to an amplitude (‘Higgs') mode7. These observations offer a viewpoint into emergent collective dynamics in strongly correlated quantum systems and non-equilibrium quantum processes.
Phase transitions and critical phenomena, Quantum simulation
A genomic history of the North Pontic Region from the Neolithic to the Bronze Age
Original Paper | Archaeology | 2025-02-04 19:00 EST
Alexey G. Nikitin, Iosif Lazaridis, Nick Patterson, Svitlana Ivanova, Mykhailo Videiko, Valentin Dergachev, Nadiia Kotova, Malcolm Lillie, Inna Potekhina, Marta Krenz-Niedbała, Sylwia Łukasik, Serhij Makhortykh, Virginie Renson, Henry Shephard, Gennadie Sirbu, Sofiia Svyryd, Taras Tkachuk, Piotr Włodarczak, Kim Callan, Elizabeth Curtis, Eadaoin Harney, Lora Iliev, Aisling Kearns, Ann Marie Lawson, Megan Michel, Matthew Mah, Adam Micco, Jonas Oppenheimer, Lijun Qiu, J. Noah Workman, Fatma Zalzala, Swapan Mallick, Nadin Rohland, David Reich
The North Pontic Region was the meeting point of the farmers of Old Europe and the foragers and pastoralists of the Eurasian steppe1,2, and the source of migrations deep into Europe3,4,5. Here we report genome-wide data from 81 prehistoric North Pontic individuals to understand the genetic makeup of its people. North Pontic foragers had ancestry from Balkan and Eastern hunter-gatherers6 as well as European farmers and, occasionally, Caucasus hunter-gatherers. During the Eneolithic period, a wave of migrants from the Caucasus-Lower Volga area7 bypassed local foragers to mix in equal parts with Trypillian farmers, forming the people of the Usatove culture around 4500 bce. A temporally overlapping wave of migrants from the Caucasus-Lower Volga blended with foragers instead of farmers to form Serednii Stih people7. The third wave was the Yamna--descendants of the Serednii Stih who formed by mixture around 4000 bce and expanded during the Early Bronze Age (3300 bce). The temporal gap between Serednii Stih and the Yamna is bridged by a genetically Yamna individual from Mykhailivka, Ukraine (3635-3383 bce), a site of archaeological continuity across the Eneolithic-Bronze Age transition and a likely epicentre of Yamna formation. Each of these three waves of migration propagated distinctive ancestries while also incorporating outsiders, a flexible strategy that may explain the success of the peoples of the North Pontic in spreading their genes and culture across Eurasia3,4,5,8,9,10.
Archaeology, Evolutionary genetics, Genetic variation, Population genetics
SKI complex loss renders 9p21.3-deleted or MSI-H cancers dependent on PELO
Original Paper | Predictive markers | 2025-02-04 19:00 EST
Patricia C. Borck, Isabella Boyle, Kristina Jankovic, Nolan Bick, Kyla Foster, Anthony C. Lau, Lucy I. Parker-Burns, Daniel A. Lubicki, Tianxia Li, Ashir A. Borah, Nicholas J. Lofaso, Sohani Das Sharma, Tessla Chan, Riya V. Kishen, Anisah Adeagbo, Srivatsan Raghavan, Elisa Aquilanti, John R. Prensner, J. Michael Krill-Burger, Todd R. Golub, Catarina D. Campbell, Joshua M. Dempster, Edmond M. Chan, Francisca Vazquez
Cancer genome alterations often lead to vulnerabilities that can be used to selectively target cancer cells. Various inhibitors of such synthetic lethal targets have been approved by the FDA or are in clinical trials, highlighting the potential of this approach1,2,3. Here we analysed large-scale CRISPR knockout screening data from the Cancer Dependency Map and identified a new synthetic lethal target, PELO, for two independent molecular subtypes of cancer: biallelic deletion of chromosomal region 9p21.3 or microsatellite instability-high (MSI-H). In 9p21.3-deleted cancers, PELO dependency emerges from biallelic deletion of the 9p21.3 gene FOCAD, a stabilizer of the superkiller complex (SKIc). In MSI-H cancers, PELO is required owing to MSI-H-associated mutations in TTC37 (also known as SKIC3), a critical component of the SKIc. We show that both cancer subtypes converge to destabilize the SKIc, which extracts mRNA from stalled ribosomes. In SKIc-deficient cells, PELO depletion induces the unfolded protein response, a stress response to accumulation of misfolded or unfolded nascent polypeptides. Together, our findings indicate PELO as a promising therapeutic target for a large patient population with cancers characterized as MSI-H with deleterious TTC37 mutations or with biallelic 9p21.3 deletions involving FOCAD.
Predictive markers, Targeted therapies
Transforming US agriculture for carbon removal with enhanced weathering
Original Paper | Carbon cycle | 2025-02-04 19:00 EST
David J. Beerling, Euripides P. Kantzas, Mark R. Lomas, Lyla L. Taylor, Shuang Zhang, Yoshiki Kanzaki, Rafael M. Eufrasio, Phil Renforth, Jean-Francois Mecure, Hector Pollitt, Philip B. Holden, Neil R. Edwards, Lenny Koh, Dimitar Z. Epihov, Adam Wolf, James E. Hansen, Steven A. Banwart, Nick F. Pidgeon, Christopher T. Reinhard, Noah J. Planavsky, Maria Val Martin
Enhanced weathering (EW) with agriculture uses crushed silicate rocks to drive carbon dioxide removal (CDR)1,2. If widely adopted on farmlands, it could help achieve net-zero emissions by 20502,3,4. Here we show, with a detailed US state-specific carbon cycle analysis constrained by resource provision, that EW deployed on agricultural land could sequester 0.16-0.30 GtCO2 yr-1 by 2050, rising to 0.25-0.49 GtCO2 yr-1 by 2070. Geochemical assessment of rivers and oceans suggests effective transport of dissolved products from EW from soils, offering CDR on intergenerational timescales. Our analysis further indicates that EW may temporarily help lower ground-level ozone and concentrations of secondary aerosols in agricultural regions. Geospatially mapped CDR costs show heterogeneity across the USA, reflecting a combination of cropland distance from basalt source regions, timing of EW deployment and evolving CDR rates. CDR costs are highest in the first two decades before declining to about US$100-150 tCO2-1 by 2050, including for states that contribute most to total national CDR. Although EW cannot be a substitute for emission reductions, our assessment strengthens the case for EW as an overlooked practical innovation for helping the USA meet net-zero 2050 goals5,6. Public awareness of EW and equity impacts of EW deployment across the USA require further exploration7,8 and we note that mobilizing an EW industry at the necessary scale could take decades.
Carbon cycle, Climate and Earth system modelling
Topological water-wave structures manipulating particles
Original Paper | Fluid dynamics | 2025-02-04 19:00 EST
Bo Wang, Zhiyuan Che, Cheng Cheng, Caili Tong, Lei Shi, Yijie Shen, Konstantin Y. Bliokh, Jian Zi
Topological wave structures, such as vortices1,2,3,4,5,6, polarization textures7,8,9,10,11 and skyrmions12,13,14,15,16,17,18,19, appear in various quantum and classical wave fields, including optics and acoustics. In particular, optical vortices have found numerous applications20,21, ranging from quantum information to astrophysics. Furthermore, both optical and acoustic structured waves are crucial in the manipulation of small particles22,23,24,25, from atoms to macroscopic biological objects. Recently, there has been a surge of interest in structured water surface waves, which can be notable analogues of quantum, optical and acoustic wave systems26,27,28,29. However, topological water-wave forms, especially their ability to manipulate particles, have not yet been demonstrated. Here we describe the controllable generation of topological structures, namely wave vortices, skyrmions and polarization Möbius strips, in gravity water waves. Most importantly, we demonstrate the efficient manipulation of subwavelength and wavelength-order floating particles with topologically structured water waves. This includes trapping the particles in the high-intensity field zones and controlling their orbital and spinning motion due to the orbital and spin angular momenta of the water waves. Our results reveal the water-wave counterpart of optical and acoustic manipulation, which paves the way for applications in hydrodynamics and microfluidics.
Fluid dynamics, Nonlinear phenomena, Optical physics, Topological matter
A comprehensive spatio-cellular map of the human hypothalamus
Original Paper | Neural circuits | 2025-02-04 19:00 EST
John A. Tadross, Lukas Steuernagel, Georgina K. C. Dowsett, Katherine A. Kentistou, Sofia Lundh, Marta Porniece, Paul Klemm, Kara Rainbow, Henning Hvid, Katarzyna Kania, Joseph Polex-Wolf, Lotte Bjerre Knudsen, Charles Pyke, John R. B. Perry, Brian Y. H. Lam, Jens C. Brüning, Giles S. H. Yeo
The hypothalamus is a brain region that plays a key role in coordinating fundamental biological functions1. However, our understanding of the underlying cellular components and neurocircuitries have, until recently, emerged primarily from rodent studies2,3. Here we combine single-nucleus sequencing of 433,369 human hypothalamic cells with spatial transcriptomics, generating a comprehensive spatio-cellular transcriptional map of the hypothalamus, the ‘HYPOMAP'. Although conservation of neuronal cell types between humans and mice, as based on transcriptomic identity, is generally high, there are notable exceptions. Specifically, there are significant disparities in the identity of pro-opiomelanocortin neurons and in the expression levels of G-protein-coupled receptors between the two species that carry direct implications for currently approved obesity treatments. Out of the 452 hypothalamic cell types, we find that 291 neuronal clusters are significantly enriched for expression of body mass index (BMI) genome-wide association study genes. This enrichment is driven by 426 ‘effector' genes. Rare deleterious variants in six of these (MC4R, PCSK1, POMC, CALCR, BSN and CORO1A) associate with BMI at population level, and CORO1A has not been linked previously to BMI. Thus, HYPOMAP provides a detailed atlas of the human hypothalamus in a spatial context and serves as an important resource to identify new druggable targets for treating a wide range of conditions, including reproductive, circadian and metabolic disorders.
Neural circuits, Obesity
RUNX2 promotes fibrosis via an alveolar-to-pathological fibroblast transition
Original Paper | Experimental models of disease | 2025-02-04 19:00 EST
Yinshan Fang, Sanny S. W. Chung, Le Xu, Chenyi Xue, Xue Liu, Dianhua Jiang, Rongbo Li, Yohei Korogi, Ke Yuan, Anjali Saqi, Hanina Hibshoosh, Yuefeng Huang, Chyuan-Sheng Lin, Tatsuya Tsukui, Dean Sheppard, Xin Sun, Jianwen Que
A hallmark of pulmonary fibrosis is the aberrant activation of lung fibroblasts into pathological fibroblasts that produce excessive extracellular matrix1,2,3. Thus, the identification of key regulators that promote the generation of pathological fibroblasts can inform the development of effective countermeasures against disease progression. Here we use two mouse models of pulmonary fibrosis to show that LEPR+ fibroblasts that arise during alveologenesis include SCUBE2+ alveolar fibroblasts as a major constituent. These alveolar fibroblasts in turn contribute substantially to CTHRC1+POSTN+ pathological fibroblasts. Genetic ablation of POSTN+ pathological fibroblasts attenuates fibrosis. Comprehensive analyses of scRNA-seq and scATAC-seq data reveal that RUNX2 is a key regulator of the expression of fibrotic genes. Consistently, conditional deletion of Runx2 with LeprcreERT2 or Scube2creERT2 reduces the generation of pathological fibroblasts, extracellular matrix deposition and pulmonary fibrosis. Therefore, LEPR+ cells that include SCUBE2+ alveolar fibroblasts are a key source of pathological fibroblasts, and targeting Runx2 provides a potential treatment option for pulmonary fibrosis.
Experimental models of disease, Mechanisms of disease
Differential protection against SARS-CoV-2 reinfection pre- and post-Omicron
Original Paper | Epidemiology | 2025-02-04 19:00 EST
Hiam Chemaitelly, Houssein H. Ayoub, Peter Coyle, Patrick Tang, Mohammad R. Hasan, Hadi M. Yassine, Asmaa A. Al Thani, Zaina Al-Kanaani, Einas Al-Kuwari, Andrew Jeremijenko, Anvar Hassan Kaleeckal, Ali Nizar Latif, Riyazuddin Mohammad Shaik, Hanan F. Abdul-Rahim, Gheyath K. Nasrallah, Mohamed Ghaith Al-Kuwari, Adeel A. Butt, Hamad Eid Al-Romaihi, Mohamed H. Al-Thani, Abdullatif Al-Khal, Roberto Bertollini, Laith J. Abu-Raddad
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly evolved over short timescales, leading to the emergence of more transmissible variants such as Alpha and Delta1,2,3. The arrival of the Omicron variant marked a major shift, introducing numerous extra mutations in the spike gene compared with earlier variants1,2. These evolutionary changes have raised concerns regarding their potential impact on immune evasion, disease severity and the effectiveness of vaccines and treatments1,3. In this epidemiological study, we identified two distinct patterns in the protective effect of natural infection against reinfection in the Omicron versus pre-Omicron eras. Before Omicron, natural infection provided strong and durable protection against reinfection, with minimal waning over time. However, during the Omicron era, protection was robust only for those recently infected, declining rapidly over time and diminishing within a year. These results demonstrate that SARS-CoV-2 immune protection is shaped by a dynamic interaction between host immunity and viral evolution, leading to contrasting reinfection patterns before and after Omicron's first wave. This shift in patterns suggests a change in evolutionary pressures, with intrinsic transmissibility driving adaptation pre-Omicron and immune escape becoming dominant post-Omicron, underscoring the need for periodic vaccine updates to sustain immunity.
Epidemiology, Viral infection
Multi-interface licensing of protein import into a phage nucleus
Original Paper | Bacteriology | 2025-02-04 19:00 EST
Claire Kokontis, Timothy A. Klein, Sukrit Silas, Joseph Bondy-Denomy
Bacteriophages use diverse mechanisms to evade antiphage defence systems. ΦKZ-like jumbo phages assemble a proteinaceous, nucleus-like compartment that excludes antagonistic host nucleases and also internalizes DNA replication and transcription machinery1,2,3,4. The phage factors required for protein import and the mechanisms of selectivity remain unknown, however. Here we uncover an import system comprising proteins highly conserved across nucleus-forming phages, together with additional cargo-specific contributors. Using a genetic selection that forces the phage to decrease or abolish the import of specific proteins, we determine that the importation of five different phage nuclear-localized proteins requires distinct interfaces of the same factor, Imp1 (gp69). Imp1 localizes early to the nascent phage nucleus and forms discrete puncta in the mature phage nuclear periphery, probably in complex with direct interactor Imp6 (gp67), a conserved protein encoded in the same locus. The import of certain proteins, including a host topoisomerase, additionally requires Imp3 (gp59), a conserved factor necessary for proper Imp1 function. Three additional non-conserved phage proteins (Imp2 and Imp4/Imp5) are required for the import of two queried nuclear cargos (nuclear-localized protein 1 and host topoisomerase, respectively), perhaps acting as specific adaptors. We therefore propose a core import system that includes Imp1, Imp3 and Imp6, with multiple interfaces of Imp1 licensing transport through a protein lattice.
Bacteriology, Bacteriophages
Children's arithmetic skills do not transfer between applied and academic mathematics
Original Paper | Economics | 2025-02-04 19:00 EST
Abhijit V. Banerjee, Swati Bhattacharjee, Raghabendra Chattopadhyay, Esther Duflo, Alejandro J. Ganimian, Kailash Rajah, Elizabeth S. Spelke
Many children from low-income backgrounds worldwide fail to master school mathematics1; however, some children extensively use mental arithmetic outside school2,3. Here we surveyed children in Kolkata and Delhi, India, who work in markets (n = 1,436), to investigate whether maths skills acquired in real-world settings transfer to the classroom and vice versa. Nearly all these children used complex arithmetic calculations effectively at work. They were also proficient in solving hypothetical market maths problems and verbal maths problems that were anchored to concrete contexts. However, they were unable to solve arithmetic problems of equal or lesser complexity when presented in the abstract format typically used in school. The children's performance in market maths problems was not explained by memorization, access to help, reduced stress with more familiar formats or high incentives for correct performance. By contrast, children with no market-selling experience (n = 471), enrolled in nearby schools, showed the opposite pattern. These children performed more accurately on simple abstract problems, but only 1% could correctly answer an applied market maths problem that more than one third of working children solved (β = 0.35, s.e.m. = 0.03; 95% confidence interval = 0.30-0.40, P < 0.001). School children used highly inefficient written calculations, could not combine different operations and arrived at answers too slowly to be useful in real-life or in higher maths. These findings highlight the importance of educational curricula that bridge the gap between intuitive and formal maths.
Economics, Education, Human behaviour
A neoantigen vaccine generates antitumour immunity in renal cell carcinoma
Original Paper | Cancer immunotherapy | 2025-02-04 19:00 EST
David A. Braun, Giorgia Moranzoni, Vipheaviny Chea, Bradley A. McGregor, Eryn Blass, Chloe R. Tu, Allison P. Vanasse, Cleo Forman, Juliet Forman, Alexander B. Afeyan, Nicholas R. Schindler, Yiwen Liu, Shuqiang Li, Jackson Southard, Steven L. Chang, Michelle S. Hirsch, Nicole R. LeBoeuf, Oriol Olive, Ambica Mehndiratta, Haley Greenslade, Keerthi Shetty, Susan Klaeger, Siranush Sarkizova, Christina B. Pedersen, Matthew Mossanen, Isabel Carulli, Anna Tarren, Joseph Duke-Cohan, Alexis A. Howard, J. Bryan Iorgulescu, Bohoon Shim, Jeremy M. Simon, Sabina Signoretti, Jon C. Aster, Liudmila Elagina, Steven A. Carr, Ignaty Leshchiner, Gad Getz, Stacey Gabriel, Nir Hacohen, Lars R. Olsen, Giacomo Oliveira, Donna S. Neuberg, Kenneth J. Livak, Sachet A. Shukla, Edward F. Fritsch, Catherine J. Wu, Derin B. Keskin, Patrick A. Ott, Toni K. Choueiri
Personalized cancer vaccines (PCVs) can generate circulating immune responses against predicted neoantigens1,2,3,4,5,6. However, whether such responses can target cancer driver mutations, lead to immune recognition of a patient's tumour and result in clinical activity are largely unknown. These questions are of particular interest for patients who have tumours with a low mutational burden. Here we conducted a phase I trial (ClinicalTrials.gov identifier NCT02950766) to test a neoantigen-targeting PCV in patients with high-risk, fully resected clear cell renal cell carcinoma (RCC; stage III or IV) with or without ipilimumab administered adjacent to the vaccine. At a median follow-up of 40.2 months after surgery, none of the 9 participants enrolled in the study had a recurrence of RCC. No dose-limiting toxicities were observed. All patients generated T cell immune responses against the PCV antigens, including to RCC driver mutations in VHL, PBRM1, BAP1, KDM5C and PIK3CA. Following vaccination, there was a durable expansion of peripheral T cell clones. Moreover, T cell reactivity against autologous tumours was detected in seven out of nine patients. Our results demonstrate that neoantigen-targeting PCVs in high-risk RCC are highly immunogenic, capable of targeting key driver mutations and can induce antitumour immunity. These observations, in conjunction with the absence of recurrence in all nine vaccinated patients, highlights the promise of PCVs as effective adjuvant therapy in RCC.
Cancer immunotherapy, Translational research, Tumour immunology
H-bonded organic frameworks as ultrasound-programmable delivery platform
Original Paper | Biomedical engineering | 2025-02-04 19:00 EST
Wenliang Wang, Yanshu Shi, Wenrui Chai, Kai Wing Kevin Tang, Ilya Pyatnitskiy, Yi Xie, Xiangping Liu, Weilong He, Jinmo Jeong, Ju-Chun Hsieh, Anakaren Romero Lozano, Brinkley Artman, Xi Shi, Nicole Hoefer, Binita Shrestha, Noah B. Stern, Wei Zhou, David W. McComb, Tyrone Porter, Graeme Henkelman, Banglin Chen, Huiliang Wang
The precise control of mechanochemical activation within deep tissues using non-invasive ultrasound holds profound implications for advancing our understanding of fundamental biomedical sciences and revolutionizing disease treatments1,2,3,4. However, a theory-guided mechanoresponsive materials system with well-defined ultrasound activation has yet to be explored5,6. Here we present the concept of using porous hydrogen-bonded organic frameworks (HOFs) as toolkits for focused ultrasound (FUS) programmably triggered drug activation to control specific cellular events in the deep brain, through on-demand scission of the supramolecular interactions. A theoretical model is developed to potentially visualize the mechanochemical scission and ultrasound mechanics, providing valuable guidelines for the rational design of mechanoresponsive materials to achieve programmable control. To demonstrate the practicality of this approach, we encapsulate the designer drug clozapine N-oxide (CNO) into the optimal HOF nanocrystals for FUS-gated release to activate engineered G-protein-coupled receptors in the ventral tegmental area (VTA) of mice and rats and hence achieve targeted neural circuit modulation even at depth 9 mm with a latency of seconds. This work demonstrates the capability of ultrasound to precisely control molecular interactions and develops ultrasound-programmable HOFs to non-invasively and spatiotemporally control cellular events, thereby facilitating the establishment of precise molecular therapeutic possibilities.
Biomedical engineering, Nanoparticles
Emergence of collective oscillations in massive human crowds
Original Paper | Biological physics | 2025-02-04 19:00 EST
François Gu, Benjamin Guiselin, Nicolas Bain, Iker Zuriguel, Denis Bartolo
Dense crowds form some of the most dangerous environments in modern society1. Dangers arise from uncontrolled collective motions, leading to compression against walls, suffocation and fatalities2,3,4. Our current understanding of crowd dynamics primarily relies on heuristic collision models, which effectively capture the behaviour observed in small groups of people5,6. However, the emergent dynamics of dense crowds, composed of thousands of individuals, remains a formidable many-body problem lacking quantitative experimental characterization and explanations rooted in first principles. Here we analyse the dynamics of thousands of densely packed individuals at the San Fermín festival (Spain) and infer a physical theory of dense crowds in confinement. Our measurements reveal that dense crowds can self-organize into macroscopic chiral oscillators, coordinating the orbital motion of hundreds of individuals without external guidance. Guided by these measurements and symmetry principles, we construct a mechanical model of dense-crowd motion. Our model demonstrates that emergent odd frictional forces drive a non-reciprocal phase transition7 towards collective chiral oscillations, capturing all our experimental observations. To test the robustness of our findings, we show that similar chiral dynamics emerged at the onset of the 2010 Love Parade disaster and propose a protocol that could help anticipate these previously unpredictable dynamics.
Biological physics, Fluid dynamics, Statistical physics, thermodynamics and nonlinear dynamics
Two-dimensional polyaniline crystal with metallic out-of-plane conductivity
Original Paper | Electronic devices | 2025-02-04 19:00 EST
Tao Zhang, Shu Chen, Petko St. Petkov, Peng Zhang, Haoyuan Qi, Nguyen Ngan Nguyen, Wenjie Zhang, Jiho Yoon, Peining Li, Thomas Brumme, Alexey Alfonsov, Zhongquan Liao, Mike Hambsch, Shunqi Xu, Lars Mester, Vladislav Kataev, Bernd Büchner, Stefan C. B. Mannsfeld, Ehrenfried Zschech, Stuart S. P. Parkin, Ute Kaiser, Thomas Heine, Renhao Dong, Rainer Hillenbrand, Xinliang Feng
Linear conducting polymers show ballistic transport, imposed by mobile carriers moving along the polymer chains1,2, whereas conductance in the extended dimension, that is, between polymer strands or layers, remains weak due to the lack of intermolecular ordering and electronic coupling3,4,5. Here we report a multilayer-stacked two-dimensional polyaniline (2DPANI) crystal, which shows metallic out-of-plane charge transport with high electrical conductivity. The material comprises columnar π arrays with an interlayer distance of 3.59 Å and periodic rhombohedral lattices formed by interwoven polyaniline chains. Electron spin resonance spectroscopy reveals significant electron delocalization in the 2DPANI lattices. First-principles calculations indicate the in-plane 2D conjugation and strong interlayer electronic coupling in 2DPANI facilitated by the Cl-bridged layer stacking. To assess the local optical conductivity, we used terahertz and infrared nanospectroscopy to unravel a Drude-type conductivity with an infrared plasma frequency and an extrapolated local d.c. conductivity of around 200 S cm-1. Conductive scanning probe microscopy showed an unusually high out-of-plane conductivity of roughly 15 S cm-1. Transport measurements through vertical and lateral micro-devices revealed comparable high out-of-plane (roughly 7 S cm-1) and in-plane conductivity (roughly 16 S cm-1). The vertical micro-devices further showed increasing conductivity with decreasing temperature, demonstrating unique out-of-plane metallic transport behaviour. By using this multilayer-stacked 2D conducting polymer design, we predict the achievement of strong electronic coupling beyond in-plane interactions, potentially reaching three-dimensional metallic conductivity6,7.
Electronic devices, Two-dimensional materials
Thermalization and criticality on an analogue-digital quantum simulator
Original Paper | Information theory and computation | 2025-02-04 19:00 EST
T. I. Andersen, N. Astrakhantsev, A. H. Karamlou, J. Berndtsson, J. Motruk, A. Szasz, J. A. Gross, A. Schuckert, T. Westerhout, Y. Zhang, E. Forati, D. Rossi, B. Kobrin, A. Di Paolo, A. R. Klots, I. Drozdov, V. Kurilovich, A. Petukhov, L. B. Ioffe, A. Elben, A. Rath, V. Vitale, B. Vermersch, R. Acharya, L. A. Beni, K. Anderson, M. Ansmann, F. Arute, K. Arya, A. Asfaw, J. Atalaya, B. Ballard, J. C. Bardin, A. Bengtsson, A. Bilmes, G. Bortoli, A. Bourassa, J. Bovaird, L. Brill, M. Broughton, D. A. Browne, B. Buchea, B. B. Buckley, D. A. Buell, T. Burger, B. Burkett, N. Bushnell, A. Cabrera, J. Campero, H.-S. Chang, Z. Chen, B. Chiaro, J. Claes, A. Y. Cleland, J. Cogan, R. Collins, P. Conner, W. Courtney, A. L. Crook, S. Das, D. M. Debroy, L. De Lorenzo, A. Del Toro Barba, S. Demura, P. Donohoe, A. Dunsworth, C. Earle, A. Eickbusch, A. M. Elbag, M. Elzouka, C. Erickson, L. Faoro, R. Fatemi, V. S. Ferreira, L. Flores Burgos, A. G. Fowler, B. Foxen, S. Ganjam, R. Gasca, W. Giang, C. Gidney, D. Gilboa, M. Giustina, R. Gosula, A. Grajales Dau, D. Graumann, A. Greene, S. Habegger, M. C. Hamilton, M. Hansen, M. P. Harrigan, S. D. Harrington, S. Heslin, P. Heu, G. Hill, M. R. Hoffmann, H.-Y. Huang, T. Huang, A. Huff, W. J. Huggins, S. V. Isakov, E. Jeffrey, Z. Jiang, C. Jones, S. Jordan, C. Joshi, P. Juhas, D. Kafri, H. Kang, K. Kechedzhi, T. Khaire, T. Khattar, M. Khezri, M. Kieferová, S. Kim, A. Kitaev, P. Klimov, A. N. Korotkov, F. Kostritsa, J. M. Kreikebaum, D. Landhuis, B. W. Langley, P. Laptev, K.-M. Lau, L. Le Guevel, J. Ledford, J. Lee, K. W. Lee, Y. D. Lensky, B. J. Lester, W. Y. Li, A. T. Lill, W. Liu, W. P. Livingston, A. Locharla, D. Lundahl, A. Lunt, S. Madhuk, A. Maloney, S. Mandrà, L. S. Martin, O. Martin, S. Martin, C. Maxfield, J. R. McClean, M. McEwen, S. Meeks, K. C. Miao, A. Mieszala, S. Molina, S. Montazeri, A. Morvan, R. Movassagh, C. Neill, A. Nersisyan, M. Newman, A. Nguyen, M. Nguyen, C.-H. Ni, M. Y. Niu, W. D. Oliver, K. Ottosson, A. Pizzuto, R. Potter, O. Pritchard, L. P. Pryadko, C. Quintana, M. J. Reagor, D. M. Rhodes, G. Roberts, C. Rocque, E. Rosenberg, N. C. Rubin, N. Saei, K. Sankaragomathi, K. J. Satzinger, H. F. Schurkus, C. Schuster, M. J. Shearn, A. Shorter, N. Shutty, V. Shvarts, V. Sivak, J. Skruzny, S. Small, W. Clarke Smith, S. Springer, G. Sterling, J. Suchard, M. Szalay, A. Sztein, D. Thor, A. Torres, M. M. Torunbalci, A. Vaishnav, S. Vdovichev, B. Villalonga, C. Vollgraff Heidweiller, S. Waltman, S. X. Wang, T. White, K. Wong, B. W. K. Woo, C. Xing, Z. Jamie Yao, P. Yeh, B. Ying, J. Yoo, N. Yosri, G. Young, A. Zalcman, N. Zhu, N. Zobrist, H. Neven, R. Babbush, S. Boixo, J. Hilton, E. Lucero, A. Megrant, J. Kelly, Y. Chen, V. Smelyanskiy, G. Vidal, P. Roushan, A. M. Läuchli, D. A. Abanin, X. Mi
Understanding how interacting particles approach thermal equilibrium is a major challenge of quantum simulators1,2. Unlocking the full potential of such systems towards this goal requires flexible initial state preparation, precise time evolution and extensive probes for final state characterization. Here we present a quantum simulator comprising 69 superconducting qubits that supports both universal quantum gates and high-fidelity analogue evolution, with performance beyond the reach of classical simulation in cross-entropy benchmarking experiments. This hybrid platform features more versatile measurement capabilities compared with analogue-only simulators, which we leverage here to reveal a coarsening-induced breakdown of Kibble-Zurek scaling predictions3 in the XY model, as well as signatures of the classical Kosterlitz-Thouless phase transition4. Moreover, the digital gates enable precise energy control, allowing us to study the effects of the eigenstate thermalization hypothesis5,6,7 in targeted parts of the eigenspectrum. We also demonstrate digital preparation of pairwise-entangled dimer states, and image the transport of energy and vorticity during subsequent thermalization in analogue evolution. These results establish the efficacy of superconducting analogue-digital quantum processors for preparing states across many-body spectra and unveiling their thermalization dynamics.
Information theory and computation, Phase transitions and critical phenomena, Quantum information, Quantum simulation, Qubits
Polytype switching by super-lubricant van der Waals cavity arrays
Original Paper | Ferroelectrics and multiferroics | 2025-02-04 19:00 EST
Youngki Yeo, Yoav Sharaby, Nirmal Roy, Noam Raab, Kenji Watanabe, Takashi Taniguchi, Moshe Ben Shalom
Expanding the performance of field-effect devices is a key challenge of the ever-growing chip industry at the core of current technologies1. Non-volatile multiferroic transistors that control atomic movements rather than purely electronic distribution are highly desired2. Recently, a field-effect control over structural transitions was achieved in commensurate stacking configurations of honeycomb van der Waals (vdW) polytypes by sliding boundary strips between oppositely polarized domains3,4,5,6. This ferroelectric hysteretic response, however, relied on pre-existing dislocation strips between relatively large micron-scale domains, severely limiting practical implementations3,7,8. Here we report the robust electric switching of single-domain polytypes in nanometre-scale islands embedded in super-lubricant vdW arrays. We etch cavities into a thin layered spacer and then encapsulate it with functional flakes. The flakes above/under the lattice-mismatched spacer sag and touch at each cavity to form islands of commensurate and metastable polytype configurations. By imaging the polarization of the polytypes, we observe nucleation and annihilation of boundary strips and geometry-adaptable ferroelectric hysteresis loops. Using mechanical stress, we further control the position of boundary strips, modify marginal twist angles and nucleate patterns of polar domain. This super-lubricant arrays of polytype (SLAP) concept suggests ‘slidetronics' device applications such as elastic-coupled neuromorphic memory cells and non-volatile multiferroic tunnelling transistors and programmable response by designing the size, shape and symmetry of the islands and of the arrays9.
Ferroelectrics and multiferroics, Two-dimensional materials
Two-Eyed Seeing and other Indigenous perspectives for neuroscience
Review Paper | Neurological disorders | 2025-02-04 19:00 EST
J. Illes, M. L. Perreault, K. Bassil, J. G. Bjaalie, R. L. Taylor-Bragge, H. Chneiweiss, T. R. Gregory, B. N. Kumar, O. P. Matshabane, A. L. Svalastog, M. R. Velarde
The integration of Indigenous perspectives and knowledge with biomedical approaches in neurosciences can significantly broaden the understanding of the human brain and mind. Drawing upon the writings of Elders in Canada, we refer to this integration as Two-Eyed Seeing or Etuaptmumk. We discuss how Two-Eyed Seeing and other dual perspectives can bring both breadth of knowledge and humility to the development of research and clinical practices for brain health. In this forward-looking discussion, we include both traditional academic and non-academic traditions and the work of Indigenous scholars on methodologies, life, health, culture, language and history. To describe challenges and consider solutions, we offer broad strategies for allyship, humility and universalism and situate them in four specific examples pertaining to disability, suicide, migration and the environment. We further advance the power of Two-Eyed Seeing in the context of new considerations for communication and public engagement. Two-Eyed Seeing, per se, is only one approach, but as neuroscience becomes ever more global, inclusive and ethically proactive, it must universally see the world of brain and mental health through the eyes of both reductionism and holism.
Neurological disorders, Neurology
Antibody prophylaxis may mask subclinical SIV infections in macaques
Original Paper | HIV infections | 2025-02-04 19:00 EST
Christopher A. Gonelli, Hannah A. D. King, SungYoul Ko, Christine M. Fennessey, Nami Iwamoto, Rosemarie D. Mason, Ashley Heimann, Dillon R. Flebbe, John-Paul Todd, Kathryn E. Foulds, Brandon F. Keele, Jeffrey D. Lifson, Richard A. Koup, Mario Roederer
Broadly neutralizing antibodies (bNAbs) show potential to prevent human immunodeficiency virus (HIV-1) infection in humans1. However, there are limited data on the antibody concentrations required to prevent infection. Clinical trials of bNAb prophylaxis have demonstrated partial efficacy2, but the sampling frequency typically does not allow precise timing of infection events and concurrent antibody levels. Here, using simian immunodeficiency virus (SIV) infection of rhesus macaques, we show that although potent bNAbs can delay the onset of acute viremia, subclinical infections occur while bNAb levels remain high. Serial SIV challenge of monkeys given partially and fully neutralizing bNAbs revealed that ‘viral blips'--low and transient plasma viremia--often occur while serum bNAb concentrations are well above currently accepted protective levels. To understand the precise timing of the infections resulting in such blips, we performed plasma viral sequencing on monkeys that were serially challenged with genetically barcoded SIV after bNAb administration. These analyses showed that subclinical infections occurred in most animals that were given potent bNAb prophylaxis. These subclinical infections occurred while antibody concentrations were 2- to 400-fold higher than the levels required to prevent fully viremic breakthrough infection. This study demonstrates that immunoprophylaxis can mask subclinical infections, which may affect the interpretation of prophylactic HIV-1 bNAb clinical trials.
HIV infections, Immunization
Millihertz oscillations near the innermost orbit of a supermassive black hole
Original Paper | Compact astrophysical objects | 2025-02-04 19:00 EST
Megan Masterson, Erin Kara, Christos Panagiotou, William N. Alston, Joheen Chakraborty, Kevin Burdge, Claudio Ricci, Sibasish Laha, Iair Arcavi, Riccardo Arcodia, S. Bradley Cenko, Andrew C. Fabian, Javier A. García, Margherita Giustini, Adam Ingram, Peter Kosec, Michael Loewenstein, Eileen T. Meyer, Giovanni Miniutti, Ciro Pinto, Ronald A. Remillard, Dev R. Sadaula, Onic I. Shuvo, Benny Trakhtenbrot, Jingyi Wang
Recent discoveries from time-domain surveys are defying our expectations for how matter accretes onto supermassive black holes (SMBHs). The increased rate of short-timescale, repetitive events around SMBHs, including the recently discovered quasi-periodic eruptions1,2,3,4,5, are garnering further interest in stellar-mass companions around SMBHs and the progenitors to millihertz-frequency gravitational-wave events. Here we report the discovery of a highly significant millihertz quasi-periodic oscillation (QPO) in an actively accreting SMBH, 1ES 1927+654, which underwent a major optical, ultraviolet and X-ray outburst beginning in 20186,7. The QPO was detected in 2022 with a roughly 18-minute period, corresponding to coherent motion on a scale of less than 10 gravitational radii, much closer to the SMBH than typical quasi-periodic eruptions. The period decreased to 7.1 minutes over 2 years with a decelerating period evolution (\(\ddot{P}\) greater than zero). To our knowledge, this evolution has never been seen in SMBH QPOs or high-frequency QPOs in stellar-mass black holes. Models invoking orbital decay of a stellar-mass companion struggle to explain the period evolution without stable mass transfer to offset angular-momentum losses, and the lack of a direct analogue to stellar-mass black-hole QPOs means that many instability models cannot explain all of the observed properties of the QPO in 1ES 1927+654. Future X-ray monitoring will test these models, and if it is a stellar-mass orbiter, the Laser Interferometer Space Antenna (LISA) should detect its low-frequency gravitational-wave emission.
Compact astrophysical objects, General relativity and gravity, High-energy astrophysics, Time-domain astronomy, Transient astrophysical phenomena
Nature Materials
YBa2Cu3O7 as a high-temperature superinductor
Original Paper | Electrical and electronic engineering | 2025-02-04 19:00 EST
Yogesh Kumar Srivastava, Teng Chen Ietro Pang, Manoj Gupta, Manukumara Manjappa, Piyush Agarwal, Jérôme Lesueur, Ranjan Singh
The magnetic behaviour of type-II superconductors is explained by a quantum vortex with a supercurrent encircling a coherence-length-sized core. In a superconducting film with a thickness of t < λL, the vortex field decays slowly as 1/r2, extending to the Pearl length \({P}_{ {\rm{L}}}=\frac{2{\lambda }_{ {\rm{L}}}^{2}}{t}\), known as the Pearl vortex, rather than diverging as log[1/r] and decaying with London penetration depth λL, as that in the Abrikosov vortex. However, the effect of the Pearl vortex on a large enhancement in the kinetic inductance has not been fully explored. Here we discovered Pearl inductance, an additional form of kinetic inductance arising from geometrical structuring of high-superconducting-transition-temperature (Tc) YBCO superconductor thin films at the Pearl length scale. This results from an extension of vortex screening supercurrents from λL to 14λL in an ultrathin metamaterial resonator of thickness λL/7, enabling terahertz superinductance. Our device shows impedance exceeding the quantum resistance limit RQ = 6.47 kΩ by 33%, offering possibilities for cutting-edge electronic, photonic and quantum devices.
Electrical and electronic engineering, Electronic devices, Metamaterials, Superconducting devices
Physical Review Letters
Dynamical Landauer Principle: Quantifying Information Transmission by Thermodynamics
Research article | Information thermodynamics | 2025-02-05 05:00 EST
Chung-Yun Hsieh
Energy transfer and information transmission are two fundamental aspects of nature. They are seemingly unrelated, while recent findings suggest that a deep connection between them is to be discovered. This amounts to asking: Can we phrase the processes of transmitting classical bits equivalently as specific energy-transmitting tasks, thereby uncovering foundational links between them? We answer this question positively by showing that, for a broad class of classical communication tasks, a quantum dynamics' ability to transmit \(n\) bits of classical information is equivalent to its ability to transmit \(n\) units of energy in a thermodynamic task. This finding not only provides an analytical correspondence between information transmission and energy extraction tasks, but also quantifies classical communication by thermodynamics. Furthermore, our findings uncover the dynamical version of Landauer's principle, showing the strong link between transmitting information and energy. In the asymptotic regime, our results further provide thermodynamic meanings for the well-known Holevo-Schumacher-Westmoreland theorem in quantum communication theory.
Phys. Rev. Lett. 134, 050404 (2025)
Information thermodynamics, Nonequilibrium & irreversible thermodynamics, Quantum channels, Quantum communication, Quantum information processing, Quantum information theory, Quantum thermodynamics, Thermodynamics
Probing Dynamics of a Two-Dimensional Dipolar Spin Ensemble Using Single Qubit Sensor
Research article | Many-body localization | 2025-02-05 05:00 EST
Kristine Rezai, Soonwon Choi, Mikhail D. Lukin, and Alexander O. Sushkov
Understanding the thermalization dynamics of quantum many-body systems at the microscopic level is among the central challenges of modern statistical physics. Here we experimentally investigate individual spin dynamics in a two-dimensional ensemble of electron spins on the surface of a diamond crystal. We use a near-surface nitrogen-vacancy center as a nanoscale magnetic sensor to probe correlation dynamics of individual spins in a dipolar interacting surface spin ensemble. We observe that the relaxation rate for each spin is significantly slower than the na"{}ve expectation based on independently estimated dipolar interaction strengths with nearest neighbors and is strongly correlated with the timescale of the local magnetic field fluctuation. We show that this anomalously slow relaxation rate is due to the presence of strong dynamical disorder and present a quantitative explanation based on dynamic resonance counting. Finally, we use resonant spin-lock driving to control the effective strength of the local magnetic fields and reveal the role of the dynamical disorder in different regimes. Our work paves the way towards microscopic study and control of quantum thermalization in strongly interacting disordered spin ensembles.
Phys. Rev. Lett. 134, 050801 (2025)
Many-body localization, Quantum metrology, Quantum sensing, Nitrogen vacancy centers in diamond, Quantum spin models
Expanding the Quantum-Limited Gravitational-Wave Detection Horizon
Research article | Gravitational wave detection | 2025-02-05 05:00 EST
Liu Tao, Mohak Bhattacharya, Peter Carney, Luis Martin Gutierrez, Luke Johnson, Shane Levin, Cynthia Liang, Xuesi Ma, Michael Padilla, Tyler Rosauer, Aiden Wilkin, and Jonathan W. Richardson
We demonstrate the potential of new adaptive optical technology to expand the detection horizon of gravitational-wave observatories. Achieving greater quantum-noise-limited sensitivity to spacetime strain hinges on achieving higher circulating laser power, in excess of 1 MW, in conjunction with highly squeezed quantum states of light. The new technology will enable significantly higher levels of laser power and squeezing in gravitational-wave detectors, by providing high-precision, low-noise correction of limiting sources of thermal distortions directly to the core interferometer optics. In simulated projections for LIGO \(\mathrm{A}+\), assuming an input laser power of 125 W and an effective injected squeezing level of 9 dB entering the interferometer, an initial concept of this technology can reduce the noise floor of the detectors by up to 20% from 200 Hz to 5 kHz, corresponding to an increment of 4 Mpc in the sky-averaged detection range for binary neutron star mergers. This work lays the foundation for one of the key technology improvements essential to fully utilize the scientific potential of the existing 4-km LIGO facilities, to observe black hole merger events past a redshift of 5, and opens a realistic pathway towards a next-generation 40-km gravitational-wave observatory in the U. S., Cosmic Explorer.
Phys. Rev. Lett. 134, 051401 (2025)
Gravitational wave detection, Gravitational wave detectors
Flavor Hierarchy of Jet Energy Correlators inside the Quark-Gluon Plasma
Research article | Jet quenching | 2025-02-05 05:00 EST
Wen-Jing Xing, Shanshan Cao, Guang-You Qin, and Xin-Nian Wang
Heavy flavor jets provide ideal tools to probe the mass effect on jet substructure in both vacuum and quark-gluon plasma. An energy-energy correlator (EEC) is an excellent jet substructure observable owning to its strong sensitivity to jet physics at different scales. We perform a complete realistic simulation on medium modification of heavy and light flavor jet EECs in heavy-ion collisions. A clear flavor hierarchy is observed for jet EECs in both vacuum and quark-gluon plasma due to the mass effect. The medium modification of inclusive jet EECs at different angular scales exhibits a very rich structure: suppression at intermediate angles, and enhancement at small and large angles, which can be well explained by the interplay of mass effect, energy loss, medium-induced radiation, and medium response. These unique features of jet EECs are shown to probe the physics of jet-medium interaction at different scales, and can be readily validated by upcoming experiments.
Phys. Rev. Lett. 134, 052301 (2025)
Jet quenching, Jets & heavy flavor physics, Quark-gluon plasma, Relativistic heavy-ion collisions
Revealing the Nature of yrast States in Neutron-Rich Polonium Isotopes
Research article | Beta decay | 2025-02-05 05:00 EST
R. Lică et al. (IDS Collaboration)
Polonium isotopes having two protons above the shell closure at \(Z=82\) show a wide variety of low-lying, high-spin isomeric states across the whole chain. The structure of neutron-deficient isotopes up to \(^{210}\mathrm{Po}\text{ }\) (\(N=126\)) is well established as they are easily produced through various methods. However, there is not much information available for the neutron-rich counterparts for which only selective techniques can be used for their production. We report on the first fast-timing measurements of yrast states up to the \({8}^{+}\) level in \(^{214,216,218}\mathrm{Po}\) isotopes produced in the \({\beta }^{- }\) decay of \(^{214,216,218}\mathrm{Bi}\) at ISOLDE, CERN. In particular, our new half-life value of 607(14) ps for the \({8}_{1}^{+}\) state in \(^{214}\mathrm{Po}\) is nearly 20 times shorter than the value available in the literature and comparable with the newly measured half-lives of 409(16) and 628(25) ps for the corresponding \({8}_{1}^{+}\) states in \(^{216,218}\mathrm{Po}\), respectively. The measured \(B(E2;{8}_{1}^{+}\rightarrow {6}_{1}^{+})\) transition probability values follow an increasing trend relative to isotope mass, reaching a maximum for \(^{216}\mathrm{Po}\). The increase contradicts the previous claims of isomerism for the \({8}^{+}\) yrast states in neutron-rich \(^{214}\mathrm{Po}\) and beyond. Together with the other measured yrast transitions, the \(B(E2)\) values provide a crucial test of the different theoretical approaches describing the underlying configurations of the yrast band. The new experimental results are compared to shell-model calculations using the KHPE and H208 effective interactions and their pairing-modified versions, showing an increase in configuration mixing when moving toward the heavier isotopes.
Phys. Rev. Lett. 134, 052502 (2025)
Beta decay, Electromagnetic transitions, Isomer decays, Lifetimes & widths, Shell model
Purcell-Enhanced Generation of Photonic Bell States via the Inelastic Scattering off Single Atoms
Research article | Atoms, ions, & molecules in cavities | 2025-02-05 05:00 EST
Jian Wang, Xiao-Long Zhou, Ze-Min Shen, Dong-Yu Huang, Si-Jian He, Qi-Yang Huang, Yi-Jia Liu, Chuan-Feng Li, and Guang-Can Guo
Single atoms trapped in optical cavities exhibit immense potential as key nodes in future quantum information processing. They have already demonstrated significant advancement in various quantum technologies, particularly regarding the generation of nonclassical light. Here, we efficiently produce genuine photonic Bell states through the inelastic scattering process off single two-level intracavity atoms. An experimental violation of the Bell inequality, arising from the interference between the probability amplitudes of two photons, validates the intrinsic nature of energy-time entanglement. Coupling atoms with an optical cavity in the Purcell regime substantially enhances the two-photon scattering. This Bell state generation process does not require atomic spin control, thereby rendering it inherently immune to decoherence effects. This work advances the comprehension of resonance fluorescence and has the potential to broaden the landscape of quantum technologies and facilitate the application of photonic Bell states.
Phys. Rev. Lett. 134, 053401 (2025)
Atoms, ions, & molecules in cavities, Cavity quantum electrodynamics, Photon statistics, Trapped atoms, Cavity resonators, Jaynes-Cummings model
Effect of Grain Geometry on the Stability of Polycrystalline Pt at the Nanoscale
Research article | Crystal phenomena | 2025-02-05 05:00 EST
Huangliu Fu, Xin Zhou, Zhipeng Gao, Zhaohui Jin, Xiuyan Li, and K. Lu
Kelvin polycrystals with geometrical packing of tetrakaidecahedra grains were regarded as the only possible stable polycrystalline structures in solids. By intensive plastic straining of Pt, we identified the existence of Kelvin polycrystals with 4 nm grains and Schwarz crystals of 2--3 nm in size connected by minimal-surface grain boundaries, both constrained by twins. We found Schwarz crystals remained stable up to 1923 K, nearly 94% of the melting point of Pt, well above the stability limit of the Kelvin polycrystals (1373 K). It means geometries of grains and their boundary networks play a crucial role in stabilizing polycrystalline face-centered-cubic metals at the nanoscale.
Phys. Rev. Lett. 134, 056101 (2025)
Crystal phenomena, Grain boundaries, Growth
Atomistic Understanding of Dislocation Climb in Nitride Semiconductors: Role of Asymmetric Jogs
Research article | Disclinations & dislocations | 2025-02-05 05:00 EST
Han Yang, Xiangru Han, Xuelin Yang, Yingming Song, Beile Chen, Zhenghao Chen, Guangxu Ju, Fujun Xu, Ning Tang, Tongjun Yu, Xinqiang Wang, Weikun Ge, Bing Huang, and Bo Shen
Effective control of dislocation climb is of fundamental interest and practical importance in tuning the mechanical and electronic properties of semiconductors. However, it remains a big challenge due to the lack of a clear understanding of its inherent mechanism, in particular, in the nitride semiconductors. In this Letter, the atomic-scale climb process of a single dislocation in GaN is observed for the first time, which undergoes an alternating five- and nine-atomic-ring transformation. Combined with first-principles calculations, we reveal that the jogs exhibiting asymmetric atomic configurations play an unexpected role in determining the different dislocation climb behaviors in GaN. Interestingly, tuning the Fermi-level position by electroactive dopants can selectively generate different species of jogs, which can consequently manipulate the dislocation climb behaviors and dislocation dissociation in a controllable way. Our findings not only highlight the significant role the asymmetric jogs play in the dislocation climb in nitrides, but also suggest a clear routine to control dislocation dynamics in semiconductors.
Phys. Rev. Lett. 134, 056102 (2025)
Disclinations & dislocations, Wide band gap systems, First-principles calculations, Transmission electron microscopy
Intrinsic Nonlinear Spin Hall Effect and Manipulation of Perpendicular Magnetization
Research article | Spintronics | 2025-02-05 05:00 EST
Hui Wang, Huiying Liu, Xukun Feng, Jin Cao, Weikang Wu, Shen Lai, Weibo Gao, Cong Xiao, and Shengyuan A. Yang
We propose an intrinsic nonlinear spin Hall effect, which enables the generation of collinearly polarized spin current in a large class of nonmagnetic materials with the corresponding linear response being symmetry forbidden. This opens a new avenue for field-free switching of perpendicular magnetization, which is required for the next-generation information storage technology. We develop the microscopic theory of this effect and clarify its quantum origin in band geometric quantities which can be enhanced by topological nodal features. Combined with first-principles calculations, we predict pronounced effects at room temperature in topological metals \({\mathrm{PbTaSe}}_{2}\) and PdGa. Our work establishes a fundamental nonlinear response in spin transport and opens the door to exploring spintronic applications based on nonlinear spin Hall effect.
Phys. Rev. Lett. 134, 056301 (2025)
Spintronics, Transport phenomena, First-principles calculations
Hidden Zero Modes and Topology of Multiband Non-Hermitian Systems
Research article | Edge states | 2025-02-05 05:00 EST
Kyle Monkman and Jesko Sirker
In a finite one-dimensional non-Hermitian system, the number of zero modes does not necessarily reflect the topology of the system. This is known as the breakdown of the bulk-boundary correspondence and has led to misconceptions about the topological protection of edge modes in such systems. Here we show why this breakdown does occur and that it typically results in hidden zero modes, extremely long-lived zero energy excitations, which are only revealed when considering the singular value instead of the eigenvalue spectrum. We point out, furthermore, that in a finite multiband non-Hermitian system with Hamiltonian \(H\), one needs to consider also the reflected Hamiltonian \(\stackrel{\texttildelow{}}{H}\), which is in general distinct from the adjoint \({H}^{\dagger{}}\), to properly relate the number of protected zeros to the winding number of \(H\).
Phys. Rev. Lett. 134, 056601 (2025)
Edge states, Non-Hermitian systems, Topology
Current-Induced Sliding Motion in a Helimagnet \({\mathrm{MnAu}}_{2}\)
Research article | Magnetic domains | 2025-02-05 05:00 EST
Yuta Kimoto, Hidetoshi Masuda, Takeshi Seki, Yoichi Nii, Jun-ichiro Ohe, Yusuke Nambu, and Yoshinori Onose
We found signatures of current-induced sliding motion in helimagnetic \(\mathrm{Mn}{\mathrm{Au}}_{2}\) thin films. An abrupt change in differential resistivity occurred at a threshold bias current in the helimagnetic state, whereas it was absent in the induced ferromagnetic state. Broadband voltage noise also emerged above the threshold current in the helimagnetic state. Based on the similarity to canonical charge and spin density wave systems, we ascribed the origin of these phenomena to the sliding motion of the helimagnetic structure.
Phys. Rev. Lett. 134, 056702 (2025)
Magnetic domains, Magnetization dynamics, Spin transfer torque, Chiral magnets, Resistivity measurements
Dynamics of Thermally Driven Domain Transformation in Ferroelectric Thin Films
Research article | Ferroelectric domains | 2025-02-05 05:00 EST
Rui Liu, Anna Gura, Theodore Sauyet, Yugang Zhang, Lutz Wiegart, Andrei Fluerasu, and Matthew Dawber
An important feature in ultrathin ferroelectric films is the spontaneous formation of nanoscale polarization domain patterns. Epitaxial strain can greatly increase the ferroelectric transition temperature such that films can be in the ferroelectric state during growth. On the other hand, depolarization fields compete with ferroelectricity in ultrathin films, and, consequently, the optimal domain configuration during growth is a moving target. Under these conditions it is readily possible for a grown film to be in a nonequilibrium domain configuration. As the energy landscape in the system is quite complex, the relaxation dynamics by which a system can evolve towards the true equilibrium configuration are also quite interesting. To capture the details of this process we used Bragg-geometry x-ray photon correlation spectroscopy (XPCS), in which x-ray scattering speckle patterns contain the information from the domain arrangements inside the film. With modest heating (\(\sim 150\text{ }^\circ{}\mathrm{C}\)) domain relaxation from \(T\) (tetragonal) to \({M}_{C}\) (monoclinic) was observed in \({\mathrm{BaTiO}}_{3}\) films grown on ultrathin ferroelectric \({\mathrm{PbTiO}}_{3}\) layers. Two-time correlation analysis reveals fascinating details associated with sticking points and reversals in the process.
Phys. Rev. Lett. 134, 056801 (2025)
Ferroelectric domains, Ferroelectricity, Thin films, X-ray photon correlation spectroscopy
Solvated Electrons in Polar Liquids as \(\\epsilon\)-Near-Zero Materials Tunable in the Terahertz Frequency Range
Research article | Dielectric properties | 2025-02-05 05:00 EST
Matthias Runge, Michael Woerner, Denys I. Bondar, and Thomas Elsaesser
Electrons in polar liquids give rise to a polaron resonance at a terahertz (THz) frequency \({\nu }_{0}\) depending on electron concentration. The impact of this resonance on light propagation is studied in experiments, where a femtosecond pump pulse generates electrons via multiphoton ionization and a THz probe pulse propagated through the excited sample is detected in a phase-resolved way. We observe a behavior characteristic for \(\\epsilon\)-near-zero materials with strongly modified phase and group velocities around \({\nu }_{0}\), and a broadening of the THz pulse envelope below \({\nu }_{0}\). Calculations based on a local-field approach reproduce the \(\\epsilon\)-near-zero behavior.
Phys. Rev. Lett. 134, 056901 (2025)
Dielectric properties, Light-matter interaction, Multiphoton or tunneling ionization & excitation, Electrons, Liquids, Terahertz techniques
Networks with Many Structural Scales: A Renormalization Group Perspective
Research article | Network formation & growth | 2025-02-05 05:00 EST
Anna Poggialini, Pablo Villegas, Miguel A. Muñoz, and Andrea Gabrielli
Scale invariance profoundly influences the dynamics and structure of complex systems, spanning from critical phenomena to network architecture. Here, we propose a precise definition of scale-invariant networks by leveraging the concept of a constant entropy-loss rate across scales in a renormalization-group coarse-graining setting. This framework enables us to differentiate between scale-free and scale-invariant networks, revealing distinct characteristics within each class. Furthermore, we offer a comprehensive inventory of genuinely scale-invariant networks, both natural and artificially constructed, demonstrating, e.g., that the human connectome exhibits notable features of scale invariance. Our findings open new avenues for exploring the scale-invariant structural properties crucial in biological and sociotechnological systems.
Phys. Rev. Lett. 134, 057401 (2025)
Network formation & growth, Network structure, Scale free & inhomogeneous networks, Finite-size scaling, Fractal analysis, Network Models, Renormalization group, Self-similarity
Physical Review X
Generation of Massively Entangled Bright States of Light during Harmonic Generation in Resonant Media
Research article | Light-matter interaction | 2025-02-05 05:00 EST
Sili Yi, Nikolai D. Klimkin, Graham Gardiner Brown, Olga Smirnova, Serguei Patchkovskii, Ihar Babushkin, and Misha Ivanov
High-harmonic generation is generally assumed to be classical. A new analysis shows how quantum correlations can give rise to nontrivial quantum states of harmonic light.
Phys. Rev. X 15, 011023 (2025)
Light-matter interaction, Quantum optics
High-Dimensional Quantum Key Distribution by a Spin-Orbit Microlaser
Research article | Angular momentum of light | 2025-02-05 05:00 EST
Yichi Zhang, Haoqi Zhao, Tianwei Wu, Zihe Gao, Li Ge, and Liang Feng
A first-of-its-kind demonstration of microlaser-enabled, high-dimensional quantum communication relies on multilevel, spin-orbit photon qubits to enhance information capacity and noise resilience.
Phys. Rev. X 15, 011024 (2025)
Angular momentum of light, Lasers, Quantum communication, Structured light
arXiv
Nonlinear Spectroscopy as a Magnon Breakdown Diagnosis and its Efficient Simulation
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-05 20:00 EST
David A. S. Kaib, Marius Möller, Roser Valenti
Identifying quantum spin liquids, magnon breakdown, or fractionalized excitations in quantum magnets is an ongoing challenge due to the ambiguity of possible origins of excitation continua occurring in linear response probes. Recently, it was proposed that techniques measuring higher-order response, such as two-dimensional coherent spectroscopy (2DCS), could resolve such ambiguities. Numerically simulating nonlinear response functions can, however, be computationally very demanding. We present an efficient Lanczos-based method to compute second-order susceptibilities \(\chi^{2}\omega_t,\omega_\tau)\) directly in the frequency domain. Applying this to extended Kitaev models describing \(\alpha\)-RuCl\(_3\), we find qualitatively different nonlinear responses between intermediate magnetic field strengths and the high-field regime. To put these results into context, we derive the general 2DCS response of partially-polarized magnets within the linear spin-wave approximation, establishing that \(\chi^2(\omega_t,\omega_\tau)\) is restricted to a distinct universal form if the excitations are conventional magnons. Deviations from this form, as predicted in our (Lanczos-based) simulations for \(\alpha\)-RuCl\(_3\), can hence serve in 2DCS experiments as direct criteria to determine whether an observed excitation continuum is of conventional two-magnon type or of different nature.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 5 figures
Speedups in nonequilibrium thermal relaxation: Mpemba and related effects
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-05 20:00 EST
Gianluca Teza, John Bechhoefer, Antonio Lasanta, Oren Raz, Marija Vucelja
Most of our intuition about the behavior of physical systems is shaped by observations at or near thermal equilibrium. However, even a thermal quench can lead to states far from thermal equilibrium, where counterintuitive, anomalous effects can occur. A prime example of anomalous thermal relaxation is the Mpemba effect, in which a system prepared at a hot temperature cools down to the temperature of the cold environment faster than an identical system prepared at a warm temperature. Although reported for water more than 2000 years ago by Aristotle, the recent observations of analogous relaxation speedups in a variety of systems have motivated the search for general explanations. We review anomalous relaxation effects, which all share a nonmonotonic dependence of relaxation time versus initial ``distance" from the final state or from the phase transition. The final state can be an equilibrium or a nonequilibrium steady state. We first review the water experiments and classify the anomalous relaxation phenomena related to the Mpemba effect. We then provide a modern definition of the Mpemba effect, focusing on the theoretical frameworks of stochastic thermodynamics, kinetic theory, Markovian dynamics, and phase transitions. We discuss the recent experimental and numerical developments that followed these theoretical advances. These developments paved the way for the prediction and observation of novel phenomena, such as the inverse Mpemba effect. The review is self-contained and introduces anomalous relaxation phenomena in single- and many-body systems, both classical and quantum. We also discuss the broader relevance of the Mpemba effect, including its relation with phase transitions and its experimental implications. We end with perspectives that connect anomalous speedups to ideas for designing optimal heating/cooling protocols, heat engines, and efficient samplers.
Statistical Mechanics (cond-mat.stat-mech)
Circular-polarization-selective perfect reflection from chiral superconductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
Junyeong Ahn, Ashvin Vishwanath
Integrating mirrors with magnetic components is crucial for constructing chiral optical cavities, which provide tunable platforms for time-reversal-asymmetric light-matter interactions. Here, we introduce single-crystal circular-polarization-selective mirrors based on chiral superconductors, which break time-reversal symmetry by themselves eliminating the need for additional components. We show that a circular-polarization-selective perfect reflection (CSPR) occurs for strong-coupling superconductors in the BCS-BEC crossover regime or beyond if the optical Hall conductivity is significant in the unit of conductivity quantum per unit layer, \(e^2/ha_z\), where \(a_z\) is the lattice constant along the surface normal. While the optical Hall conductivity in chiral superconductors is typically tiny, we classify three routes to obtain a large value. We demonstrate the significant optical Hall conductivity and the resulting CSPR with two examples: (1) superconductivity in doped quantum Hall insulators and (2) chiral pairing that preserves the Bogoliubov Fermi surfaces in the weak-pairing limit. We also discuss the application of our theory to the recently discovered chiral superconducting phase in rhombohedral graphene. Our theory reveals the potential of these classes of chiral superconductors as promising elements for building high-quality-factor terahertz chiral cavities.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
10 pages, 5 figures
Resonance Raman Scattering and Anomalous Anti-Stokes Phenomena in CrSBr
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
Satyam Sahu, Charlotte Berrezueta-Palacios, Sabrina Juergensen, Kseniia Mosina, Zdeněk Sofer, Matěj Velický, Patryk Kusch, Otakar Frank
CrSBr, a van der Waals material, stands out as an air-stable magnetic semiconductor with appealing intrinsic properties such as crystalline anisotropy, quasi-1D electronic characteristics, layer-dependent antiferromagnetism, and non-linear optical effects. In this study, we investigate the differences between the absorption and emission spectra, focusing on the origin of the emission peak near 1.7 eV observed in the photoluminescence spectrum of CrSBr. Our findings are corroborated by excitation-dependent Raman experiments. Additionally, we explore the anti-Stokes Raman spectra and observe an anomalously high anti-Stokes to Stokes intensity ratio of up to 0.8, which varies significantly with excitation laser power and crystallographic orientation relative to the polarization of the scattered light. This ratio is notably higher than that observed in graphene (\(\approx\) 0.1) and MoS\(_2\) (\(\approx\) 0.4), highlighting the unique vibrational and electronic interactions in CrSBr. Lastly, we examine stimulated Raman scattering and calculate the Raman gain in CrSBr, which attains a value of 1 \(\times\) 10\(^{8}\) cm/GW, nearly four orders of magnitude higher than that of previously studied three-dimensional systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
22 pages, 4 figures
Machine Learning-Driven Analytical Models for Threshold Displacement Energy Prediction in Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Rosty B. Martinez Duque, Arman Duha, Mario F. Borunda
Understanding the behavior of materials under irradiation is crucial for the design and safety of nuclear reactors, spacecraft, and other radiation environments. The threshold displacement energy (Ed) is a critical parameter for understanding radiation damage in materials, yet its determination often relies on costly experiments or simulations. This work leverages the machine learning-based Sure Independence Screening and Sparsifying Operator (SISSO) method to derive accurate, analytical models for predicting Ed using fundamental material properties. The models outperform traditional approaches for monoatomic materials, capturing key trends with high accuracy. While predictions for polyatomic materials highlight challenges due to dataset complexity, they reveal opportunities for improvement with expanded data. This study identifies cohesive energy and melting temperature as key factors influencing Ed, offering a robust framework for efficient, data-driven predictions of radiation damage in diverse materials.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
18 pages, 9 figures. For associated files, see this https URL
Universal Superconductivity in FeTe and All-Iron-Based Ferromagnetic Superconductor Heterostructures
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-05 20:00 EST
Hee Taek Yi, Xiong Yao, Deepti Jain, Ying-Ting Chan, An-Hsi Chen, Matthew Brahlek, Kim Kisslinger, Kai Du, Myung-Geun Han, Yimei Zhu, Weida Wu, Sang-Wook Cheong, Seongshik Oh
Ferromagnetism (FM) and superconductivity (SC) are two of the most famous macroscopic quantum phenomena. However, nature normally does not allow SC and FM to coexist without significant degradation. Here, we introduce the first fully iron-based SC/FM heterostructures, composed of Fe(Te,Se) and Fe3GeTe2, and show that in this platform strong FM and high-temperature SC robustly coexist. We subsequently discover that chemical proximity effect from neighboring layers can universally drive the otherwise non-superconducting FeTe films into a SC state. This suggests that the ground state of FeTe is so close to the SC state that it could be driven in and out of the SC state with various other perturbations. Altogether, this shows that Fe-Te-based heterostructures provide a unique opportunity to manipulate magnetism, superconductivity and topological physics, paving the way toward new superconducting technologies.
Superconductivity (cond-mat.supr-con)
Adv. Funct. Mater. 2025, 2418259
RKKY quadratic and biquadratic spin-spin interactions in twisted bilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
D. O. Oriekhov, T. T. Osterholt, R. A. Duine, V. P. Gusynin
We study the competition between the RKKY quadratic and biquadratic spin-spin interactions of two magnetic impurities in twisted bilayer graphene away from the magic angle. We apply the Bistritzer-MacDonald model of two graphene layers twisted with respect to each other by a small angle. By reducing the model to the Dirac-type one with modified Fermi velocity, we derive expressions for the RKKY quadratic and biquadratic spin interactions using perturbation theory for the free energy. The biquadratic interaction is suppressed by a larger power of the interaction constant and decreases faster with a the distance between impurities comparing to the quadratic one. Nevertheless, due to the different period of oscillations with impurity separation distance, chemical potential, twist angle and temperature, it is possible to fine-tune the system to the regime of dominating biquadratic interaction. Such a regime might be characterized by non-conventional spin order parameters such as quadrupole order.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 5 figures
Observation of quantum oscillations, linear magnetoresistance, and crystalline electric field effect in quasi-two-dimensional PrAgBi\(_2\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-05 20:00 EST
Sudip Malick, Hanna Świątek, Michał J Winiarski, Tomasz Klimczuk
We report the magnetic and magnetotransport properties with electronic band structure calculation of the Bi square net system PrAgBi\(_2\). The magnetization and heat capacity data confirm the presence of a crystalline electric field (CEF) effect in PrAgBi\(_2\). Analysis of the CEF effect using a multilevel energy scheme reveals that the ground state of PrAgBi\(_2\) consists of five singlets and two doublets. The de Haas-van Alphen (dHvA) quantum oscillations data show a single frequency with a very small cyclotron effective mass of approximately 0.11 \(m_e\). A nontrivial Berry phase is also observed from the quantum oscillations data. The magnetotransport data shows linear and unsaturated magnetoresistance, reaching up to 1060% at 2 K and 9 T. Notably, there is a crossover from a weak-field quadratic dependence to a high-field linear dependence in the field-dependent magnetoresistance data. The crossover critical field \(B^\ast\) follows the quadratic temperature dependence, indicating the existence of Dirac fermions. The band structure calculation shows several Dirac-like linear band dispersions near the Fermi level and a Dirac point close to the Fermi level, located at the Brillouin zone boundary. calculations allowed us to ascribe the observed dHvA oscillation frequency to a particular feature of the Fermi surface. Our study suggests layered PrAgBi\(_2\) is a plausible candidate for hosting the CEF effect and Dirac fermion in the Bi square net.
Strongly Correlated Electrons (cond-mat.str-el)
12 pages, 6 figures
Phys. Rev. B 111, 045144 (2025)
Creation, stabilization, and study at ambient pressure of pressure-induced superconductivity in Bi\(_{0.5}\)Sb\(_{1.5}\)Te\(_3\)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-05 20:00 EST
Liangzi Deng (1), Busheng Wang (2), Clayton Halbert (3), Daniel J. Schulze (1), Melissa Gooch (1), Trevor Bontke (1), Ting-Wei Kuo (1 and 4), Xin Shi (1), Shaowei Song (1), Nilesh Salke (5), Hung-Duen Yang (4), Zhifeng Ren (1), Russell J. Hemley (3 and 5 and 6), Eva Zurek (2), Rohit P. Prasankumar (7), Ching-Wu Chu (1) ((1) Department of Physics and Texas Center for Superconductivity at the University of Houston (TcSUH), Houston, Texas, USA, (2) Department of Chemistry, University at Buffalo, Buffalo, New York, USA (3) Department of Chemistry, University of Illinois Chicago, Chicago, Illinois, USA, (4) Department of Physics, National Sun Yet-Sen University, Kaohsiung, Taiwan, (5) Department of Physics, University of Illinois Chicago, Chicago, Illinois, USA, (6) Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, Illinois, USA, (7) Enterprise Science Fund, Intellectual Ventures, Bellevue, Washington, USA)
In light of breakthroughs in superconductivity under high pressure, and considering that record critical temperatures (T\(_c\)s) across various systems have been achieved under high pressure, the primary challenge for higher Tc should no longer solely be to increase T\(_c\) under extreme conditions but also to reduce, or ideally eliminate, the need for applied pressure in retaining pressure-induced or -enhanced superconductivity. The topological semiconductor Bi\(_{0.5}\)Sb\(_{1.5}\)Te\(_3\) (BST) was chosen to demonstrate our approach to addressing this challenge and exploring its intriguing physics. Under pressures up to ~ 50 GPa, three superconducting phases (BST-I, -II, and -III) were observed. A superconducting phase in BST-I appears at ~ 4 GPa, without a structural transition, suggesting the possible topological nature of this phase. Using the pressure-quench protocol (PQP) recently developed by us, we successfully retained this pressure-induced phase at ambient pressure and revealed the bulk nature of the state. Significantly, this demonstrates recovery of a pressure-quenched sample from a diamond anvil cell at room temperature with the pressure-induced phase retained at ambient pressure. Other superconducting phases were retained in BST-II and -III at ambient pressure and subjected to thermal and temporal stability testing. Superconductivity was also found in BST with T\(_c\) up to 10.2 K, the record for this compound series. While PQP maintains superconducting phases in BST at ambient pressure, both depressurization and PQP enhance its T\(_c\), possibly due to microstructures formed during these processes, offering an added avenue to raise T\(_c\). These findings are supported by our density-functional theory calculations.
Superconductivity (cond-mat.supr-con)
26 pages, 14 figures
Suppression of ferromagnetism in rippled La\(_{2/3}\)Sr\(_{1/3}\)MnO\(_3\) membrane with process-induced strain prepared by epitaxial lift-off technique
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Kota Kanda, Ryuji Atsumi, Takamasa Usami, Takumi Yamazaki, Kohei Ueda, Takeshi Seki, Shigeki Miyasaka, Jobu Matsuno, Junichi Shiogai
Transition metal oxides are a platform for exploring strain-engineered intriguing physical properties and developing spintronic or flexible electronic functionalities owing to strong coupling of spin, charge and lattice degrees of freedom. In this study, we exemplify the strain-engineered magnetism of La\(_{2/3}\)Sr\(_{1/3}\)MnO\(_3\) in freestanding and rippled membrane forms without and with process-induced strain, respectively, prepared by epitaxial lift-off technique. We find that the deposition of Pt/Ti stressor suppresses the crack formation in the lift-off process and induces a ripple structure in the La\(_{2/3}\)Sr\(_{1/3}\)MnO\(_3\) membrane. Laser micrograph and Raman spectroscopy show a ripple period of about 30 um and a height of a few um, where alternating convex and concave structures are subjected to tensile strain of 0.6% and compressive strain of 0.5%, respectively. While the freestanding La\(_{2/3}\)Sr\(_{1/3}\)MnO\(_3\) membrane exhibits room-temperature ferromagnetism, the macroscopic magnetic transition temperature (TC) of the rippled membrane is reduced by as large as 27%. Temperature-variable Kerr microscopy observation in the rippled membrane reveals that the spatial variation of TC to be approximately 4% of the macroscopic TC, which coincides with the local strains at convex and concave structures. The large reduction of macroscopic TC in the rippled membrane may be ascribed to the lattice disorders due to strain gradient. Our demonstration of tuning ferromagnetism by the ripple structure validates the high potential of the process-induced strain in epitaxial lift-off technique and paves the way for strain-mediated emerging physical properties in various transition metal oxides.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Adiabatic transverse thermoelectric conversion enhanced by heat current manipulation in artificially tilted multilayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Fuyuki Ando, Takamasa Hirai, Hiroto Adachi, Ken-ichi Uchida
We phenomenologically formulate and experimentally observe an adiabatic transverse thermoelectric conversion enhanced by a heat current re-orientation in artificially tilted multilayers (ATMLs). By alternately stacking two materials with different thermal conductivities and rotating its multilayered structure with respect to a longitudinal temperature gradient, off-diagonal components in the thermal conductivity tensor are induced. This off-diagonal thermal conduction (ODTC) generates a finite transverse temperature gradient and Seebeck-effect-induced thermopower in the adiabatic condition, which is superposed on the isothermal transverse thermopower driven by the off-diagonal Seebeck effect (ODSE). In this study, we calculate and observe the two-dimensional temperature distribution and the resultant transverse thermopower in ATMLs comprising thermoelectric Co\(_{2}\)MnGa Heusler alloys and Bi\(_{2-a}\)Sb\(_{a}\)Te\(_{3}\) compounds. By changing the tilt angle from 0° to 90°, the transverse temperature gradient obviously appeared in the middle angles and the transverse thermopower increases up to -116.1 \({\mu}\)V/K in Co\(_{2}\)MnGa/Bi\(_{0.2}\)Sb\(_{1.8}\)Te\(_{3}\)-based ATML at the tilt angle of 45° whereas the isothermal contribution is estimated to be -82.6 \({\mu}\)V/K from the analytical calculation. This hybrid action derived from ODTC results in the significant variation of the maximum reduced efficiency for transverse thermoelectric conversion from 3.1% in the isothermal limit to 8.1% in the adiabatic limit.
Materials Science (cond-mat.mtrl-sci)
12 pages, 6 figures
Pressure-induced structural and superconducting transitions in black arsenic
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-05 20:00 EST
Y. Y. Wu, L. Mu, Y. L. Zhang, D. Z. Dai, K. Meng, S. Y. Huang, X. Zhang, S. C. Huang, J. Chen, H. G. Yan, S. Y. Li
We report high-pressure Raman spectra and resistance measurements of black arsenic (b-As) up to 58 GPa, along with phonon density of states (DOS) and enthalpy calculations for four reported arsenic phases up to 50 GPa. It is found that metastable b-As transforms into gray arsenic (g-As) phase at a critical pressure of 1.51 GPa, followed by subsequent transitions to simple cubic arsenic (c-As) and incommensurate host-guest arsenic (hg-As) phases at 25.9 and 44.8 GPa, respectively. Superconductivity emerges above 25 GPa in the c-As phase, with the superconducting transition temperature (\(T\)
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 5 figures, accepted by Physical Review B
Complex entanglement entropy for complex conformal field theory
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-05 20:00 EST
Haruki Shimizu, Kohei Kawabata
Conformal field theory underlies critical ground states of quantum many-body systems. While conventional conformal field theory is associated with positive central charges, nonunitary conformal field theory with complex-valued central charges has recently been recognized as physically relevant. Here, we demonstrate that complex-valued entanglement entropy characterizes complex conformal field theory and critical phenomena of open quantum many-body systems. This is based on non-Hermitian reduced density matrices constructed from the combination of right and left ground states. Applying the density matrix renormalization group to non-Hermitian systems, we numerically calculate the complex entanglement entropy of the non-Hermitian five-state Potts model, thereby confirming the scaling behavior predicted by complex conformal field theory.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
9 pages, 3 figures
Conductivity of high-mobility epitaxial GdN
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Edward X. M. Trewick, B. J. Ruck, W. F. Holmes-Hewett, H. J. Trodahl
We report electron transport studies of a (001) GdN film grown on the square net presented by the (001) surface of LaAlO3, motivated by recent advances in epitaxial thin-film growth of several lanthanide nitrides. The film we have grown for the purpose is characterised by in-situ RHEED and ex-situ XRD and XRR to show the best crystallinity and smoothest surfaces we have accomplished to date. It shows a clear ferromagnetic transition at \(\sim70\) K with a saturation magnetisation within uncertainly of 7 \(\mu\)B/Gd\(^{3+}\) ion, a remanence of 5 \(\mu\)B/Gd\(^{3+}\) ion and a coercive field of $$5 mT. It is doped by \(\sim1\)% nitrogen vacancies that introduce \(\sim3\times10^{20}\) cm\(^{-3}\) electrons into the conduction band. The resistivity shows transport in a conduction band doped to degeneracy by \(\sim0.01\) electrons/formula unit with a residual resistance ratio of 2 and a Hall resistivity permitting easily-separated ordinary and anomalous Hall components. The mobility is an order of magnitude larger than we have found in earlier films.
Materials Science (cond-mat.mtrl-sci)
6 pages, 6 figures
Magnetic field imaging with an optical microscope using a quantum diamond sensor add-on
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Alex Shaji (1), David A. Broadway (1), Philipp Reineck (1), Kevin J. Rietwyk (1), Jean-Philippe Tetienne (1) ((1) School of Science, RMIT University, Melbourne, VIC, Australia)
Widefield magnetic imaging using ensembles of nitrogen-vacancy (NV) centres in diamond has emerged as a useful technique for studying the microscopic magnetic properties of materials. Thus far, this technique has mainly been implemented on custom-made optical microscopes. We have developed an add-on for a standard laboratory optical microscope that integrates the NV-diamond sensor and necessary light source, microwave antenna, and bias magnet, enabling NV-based magnetic imaging while retaining the typical optical measurements modes of the microscope. We demonstrate our retrofitted quantum diamond microscope by imaging a magnetic particle sample using brightfield, darkfield, and magnetic imaging modes. Furthermore, we employ an iso-magnetic field imaging technique to visualise the magnetic field of the sample within seconds, and finally demonstrate three-dimensional stray field imaging. Retrofitting existing microscopes exploits the stability and high quality of traditional optical microscope systems while reducing the cost and space requirements of establishing a standalone magnetic imaging system.
Materials Science (cond-mat.mtrl-sci)
Majorana flat bands and anomalous proximity effects in \(p\)-wave magnet--superconductor hybrid systems
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-05 20:00 EST
Yutaro Nagae, Leo Katayama, Satoshi Ikegaya
Flat-band Majorana bound states of nodal \(p\)-wave superconductors give rise to striking electromagnetic anomalies, reflecting their high degree of degeneracy at the Fermi level. However, experimental investigations of these states have been hindered by the scarcity of materials exhibiting intrinsic \(p\)-wave superconductivity. In this Letter, we show that Majorana flat bands can emerge in a hybrid system consisting of a conventional superconductor and a \(p\)-wave magnet, a recently proposed class of unconventional magnets that possess a unique composite symmetry known as the \([C_{2\perp}||\boldsymbol{t}]\) symmetry. The degeneracy of the flat-band Majorana bound states is protected by chiral symmetry from the BDI symmetry class, which originates from the \([C_{2\perp}||\boldsymbol{t}]\) symmetry of the \(p\)-wave magnet. Furthermore, we predict the robust appearance of a zero-bias conductance peak in a dirty normal-metal--superconductor junction containing a \(p\)-wave magnet, which serves as an unambiguous signature of anomalous proximity effects associated with the Majorana flat bands.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Direct derivation of anisotropic atomic displacement parameters from molecular dynamics simulations demonstrated in thermoelectric materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Atomic displacement parameters (ADPs) are crystallographic information that describe the statistical distribution of atoms around an atom site. Direct derivation of anisotropic ADPs by atom from molecular dynamics (MD) simulations, where the (co)valences of atom positions are taken over recordings at different time steps in a single MD simulation, was demonstrated on three thermoelectric materials, Ag8SnSe6, Na2In2Sn4, and BaCu1.14In0.86P2. Unlike the very frequently used lattice dynamics approach, the MD approach can obtain ADPs in disordered crystals and at finite temperature, but not under conditions where atoms migrate in the crystal. ADPs from MD simulations would act as a tool complementing experimental efforts to understand the crystal structure including the distribution of atoms around atom sites.
Materials Science (cond-mat.mtrl-sci)
Valley Gapless Semiconductor: Models and Applications
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
Kok Wai Lee, Pei-Hao Fu, Jun-Feng Liu, Ching Hua Lee, Yee Sin Ang
The emerging field of valleytronics harnesses the valley degree of freedom of electrons, akin to how electronic and spintronic devices utilize the charge and spin degrees of freedom of electrons respectively. The engineering of valleytronic devices typically relies on the coupling between valley and other degrees of freedom such as spin, giving rise to valley-spintronics where an external magnetic field manipulates the information stored in valleys. Here, the valley gapless semiconductor is proposed as a potential electrically controlled valleytronic platform because the valley degree of freedom is coupled to the carrier type, i.e., electrons and holes. The valley degree of freedom can be electrically controlled by tuning the carrier type via the device gate voltage. We demonstrate the proposal for realizing a valley gapless semiconductor in the honeycomb lattice with the Haldane and modified Haldane models. The system's valley-carrier coupling is further studied for its transport properties in an all-electrically controlled valley filter device setting. Our work highlights the significance of the valley gapless semiconductor for valleytronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 3 figures
Enhanced Non-Ohmic Drain Resistance of 2DFETs at Cryogenic Temperature
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
The contact issue for two-dimensional (2D) materials-based field-effect transistors (FETs) has drawn enormous attention in recent years. Although ohmic behavior is achieved at room temperature, the drain current of 2DFETs shifts from ohmic to non-ohmic behavior at cryogenic temperatures. In this work, we demonstrate that the shift is attributed to the asymmetric current reduction at the metal-semiconductor contact at low temperature. Under low drain bias, carriers tunnel from the source to the channel but diffuse to the drain side due to the channel-to-drain barrier, resulting in the current suppression. By studying the property of ohmic metal-semiconductor contact at different temperatures, we analyzed the mechanisms behind this phenomenon and the dependence on metal-to-semiconductor barrier height. The work opens the semiconductor physics of 2D material contact at cryogenic temperature and the importance of contact metal selection in the development of 2DFET at cryogenic temperature.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
13 pages, 5 figures
Strain-induced proximity effect in topological insulator TaSe\(_3\)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-05 20:00 EST
R.M. Lukmanova, I.A. Cohn, V.E. Minakova, S.V. Zaitsev-Zotov
The magnetoresistance of superconductor-topological insulator-superconductor structures, with indium as the superconductor and TaSe\(_3\) as the topological insulator, shows stepwise resistance dependencies on an applied magnetic field. These resistance steps result from the suppression of superconductivity, induced by the proximity effect in both the bulk and surface states of the topological insulator. The position and amplitude of the steps, occurring at approximately 0.1 T, exhibit unusual dependence on the magnitude of uniaxial strain \(\epsilon\). This behavior follows the expected transition sequence: semi-metal -- strong topological insulator -- trivial dielectric and proves the appearance of the surface states at \(0.46\% \lesssim \epsilon \lesssim 1\%\).
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
5 pages, 6 figures
Silicon nitride resistance switching MIS cells doped with silicon atoms
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
A Mavropoulis, N Vasileiadis, C Bonafos, P Normand, V Ioannou-Sougleridis, G Ch Sirakoulis, P Dimitrakis
Stoichiometric SiNx layers (x = [N]/[Si] = 1.33) are doped with Si atoms by ultra-low energy ion implantation (ULE-II) and subsequently annealed at different temperatures in inert ambient conditions. Detailed material and memory cells characterization is performed to investigate the effect of Si dopants on the switching properties and performance of the fabricated resistive memory cells. In this context extensive dc current-voltage and impedance spectroscopy measurements are carried out systematically and the role of doping in dielectric properties of the nitride films is enlightened. The dc and ac conduction mechanisms are investigated in a comprehensive way. Room temperature retention characteristics of resistive states are also presented.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
arXiv admin note: text overlap with arXiv:2502.01350
Role of Molecular Structure in Defining the Dynamical Landscape of Deep Eutectic Solvents at Nanoscale
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-05 20:00 EST
T. Rinesh, H. Srinivasan, V.K. Sharma, V. García Sakai, S. Mitra
The molecular dynamics of deep eutectic solvents (DESs) are complex, characterized by nanoscale spatial and temporal heterogeneity. Understanding these dynamics is crucial for tailoring transport properties like diffusion, viscosity and ionic conductivity. Molecular diffusion in DESs stems from transient caging and translation jumps, necessitating an understanding of how molecular structure regulates these processes. This study explores the influence of alkyl chain length on the nanoscopic dynamics of alkylamide-lithium perchlorate based DESs using quasielastic neutron scattering (QENS) and molecular dynamics (MD) simulations. QENS results show that, despite its shorter chain length and lighter mass, acetamide (ACM) exhibited the lowest mobility among the alkylamides, including propanamide (PRM) and butyramide (BUT). Detailed analysis of QENS data reveals that long-range jump diffusion is fastest in ACM and slowest in BUT, essentially due to their differences in molecular size, mass and also enhanced complexation in longer alkyl chain molecules. However, the localized dynamics follows an unusual trend, where PRM is the fastest and ACM is the slowest. Despite greater flexibility in BUT, the slower caged dynamics impedes its localized motion. These findings highlight the interplay between alkyl chain length and DES dynamics, emphasizing role of molecular structure in governing transport properties.
Soft Condensed Matter (cond-mat.soft), Other Condensed Matter (cond-mat.other), Chemical Physics (physics.chem-ph)
High-pressure modulation of breathing kagome lattice: Cascade of Lifshitz transitions and evolution of the electronic structure
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-05 20:00 EST
Marcos V. Gonçalves-Faria, Maxim Wenzel, Yuk Tai Chan, Olga Iakutkina, Francesco Capitani, Davide Comboni, Michael Hanfland, Qi Wang, Hechang Lei, Martin Dressel, Alexander A. Tsirlin, Alexej Pashkin, Stephan Winnerl, Manfred Helm, Ece Uykur
The interplay between electronic correlations, density wave orders, and magnetism gives rise to several fascinating phenomena. In recent years, kagome metals have emerged as an excellent platform for investigating these unique properties, which stem from their itinerant carriers arranged in a kagome lattice. Here, we show that electronic structure of the prototypical kagome metal, Fe\(_3\)Sn\(_2\), can be tailored by manipulating the breathing distortion of its kagome lattice with external pressure. The breathing distortion is suppressed around 15 GPa and reversed at higher pressures. These changes lead to a series of Lifshitz transitions that we detect using broadband and transient optical spectroscopy. Remarkably, the strength of the electronic correlations and the tendency to carrier localization are enhanced as the kagome network becomes more regular, suggesting that breathing distortion can be a unique control parameter for the microscopic regime of the kagome metals and their electron dynamics.
Strongly Correlated Electrons (cond-mat.str-el)
Main text (4 figures) + Supplementary Materials (4 figures)
Undamped soliton-like domain wall motion in sliding ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Yubai Shi, Ri He, Hua Wang, Yuxiang Gao, Binwen Zhang, Zhicheng Zhong
Sliding ferroelectricity, which is a unique polarity recently discovered in bilayer van der Waals materials, achieves polarization switching through in-plane interlayer sliding. The unique mechanism, combining intralayer stiffness and interlayer slipperiness, leads to wider domain walls (DWs) and faster DW motion compared to conventional ferroelectrics. Herein, using machine-learning-assisted molecular dynamics simulations and field theory analysis, we find the DW in classical sliding ferroelectric bilayer 3R-MoS2 system exhibits uniformly accelerated motion under an external field, like the Newtonian particle with undamped motion. Remarkably, DW velocity remains constant even after the external field removal, completely deviating from the velocity breakdown observed in conventional ferroelectrics. We further propose an experimental approach to validate this undamped soliton-like DW behavior in sliding ferroelectric systems.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Strengthening by softening: Rigidity increase of a curved sheet from nonlinear regime of deformation
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-05 20:00 EST
Nino Quillent-Elinguel, Thomas Barois
It is well-known that a thin sheet held in a rigid circular clamp has a larger flexural strength than when it is flat. Here, we report that the flexural strength of curved sheets is further increased with a softening of the clamping condition. This unexpected compliance effect relates to the geometrical properties of curvature-induced rigidity that we observe in controlled experiments and further analyze with numerical simulations. In addition, we identify another compliance effect in which opened curved sheets can be more resistant to bending than closed cylinders of same dimensions.
Soft Condensed Matter (cond-mat.soft)
Dislocations and plasticity of KTaO\(_3\) perovskite modeled with a new interatomic potential
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Pierre Hirel, Franck Junior Kakdeu Yewou, Jiawen Zhang, Wenjun Lu, Xufei Fang, Philippe Carrez
Potassium tantalate KTaO3 is a cubic, paraelectric perovskite ceramic that exhibits surprising ductility at room temperature as most recently reported. Much like strontium titanate (SrTiO3), plastic deformation is accommodated by dislocations gliding in {110} planes. In this work we propose a new interatomic potential for KTaO3, and apply it to model dislocations with <110> Burgers vector. We demonstrate that dislocations dissociate, and finely characterize their core structure and Peierls potential. Dislocations of edge character can carry a positive or negative electric charge, but we show that charge-neutral configurations are energetically more favorable. We also perform high-resolution electron microscopy to validate our simulation methodology. Comparing our results with other ductile perovskites, we confirm KTaO3 to be ductile, but stiffer than SrTiO3.
Materials Science (cond-mat.mtrl-sci)
26 pages, 8 figures
Topological Josephson vortices at finite voltage bias
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-05 20:00 EST
Kiryl Piasotski, Adrian Reich, Alexander Shnirman
We study the effects of finite voltage bias on Caroli-de Gennes-Matricon (CdGM) states in topological Josephson junctions with a vortex lattice. The voltage drives vortices into steady motion, squeezing the CdGM spectrum due to quasi-relativistic dispersion. A finite voltage range allows well-defined states, but beyond a critical breakdown voltage, the states collapse to zero energy and become sharply localized, marking a dynamical transition. Additionally, finite bias modifies selection rules for CdGM state transitions. Notably, in the steady-state regime, the time-averaged current vanishes, revealing a novel interplay between vortex dynamics and quantum coherence.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Relationship between polymorphic structures and magnetic properties of La\(_{2-x}A'_{x}\)Ni\(_{7}\) compounds (\(A\)' = Sm, Gd)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Valérie Paul-Boncour, Véronique Charbonnier, Nicolas Madern, Lotfi Bessais, Judith Monnier, Junxian Zhang
In this study, the crystal structure and magnetic properties of La\(_{2-x} A'_{x}\)Ni\(_{7}\) compounds with magnetic rare earth elements (\(A\)' = Sm, Gd) have been investigated combining X-ray powder diffraction and magnetic measurements. These intergrowth compounds crystallize in a mixture of 2\(H\) hexagonal (Ce\(_{2}\)Ni\(_{7}\)-type) and 3\(R\) rhombohedral (Gd\(_{2}\)Co\(_{7}\)-type) polymorphic structures which are related to the stacking of [\(AB_{5}\)] and [\(A_{2}B_{4}\)] subunits along the \(c\)-this http URL average cell volume decreases linearly versus \(A\)' content, whereas the \(c/a\) ratio reaches a minimum at \(x\) = 1, due to geometric constraints upon \(A\)' for La substitution between the two different subunits. The magnetic properties strongly depend on the structure type and the \(A\)' content. Hexagonal La\(_{2}\)Ni\(_{7}\) is a weak antiferromagnet (wAFM) at low field and temperature and undergoes metamagnetic transitions towards weak ferromagnetic state (wFM) under applied field. Under an applied field of 0.1 T, La\(_{2-x}A'_{x}\)Ni\(_{7}\) intermetallic compounds display two different transition temperatures \(T_{1}\) and \(T_{2}\) that both increase with \(x\). \(T_{1}\) is associated with a wFM-wAFM transition in the 2\(H\) phase for \(A\)'= Sm, whereas \(T_{2}\) is related to the Curie temperature of both 2\(H\) and 3\(R\) phases. A metamagnetic behaviour is observed between \(T_{1}\) and \(T_{2}\) with transition field \(\mu_{0}H_{Trans}\) between 2 and 3.5 T for compounds with \(A\)' = Sm. The La\(_{2-x}Sm_{x}\)Ni\(_{7}\) compounds (\(x\) > 0} behave as hard magnets with a large coercive field \(\mu_{0}H_{C}\) at low temperature (\(\mu_{0}H_{C}\) > 9 T at 5 K for \(x\) = 2), whereas the La\(_{2-x} Gd_{x}\)Ni\(_{7}\) compounds (\(x\) > 0) are soft ferrimagnets with a linear increase of the saturation magnetization versus Gd content.
Materials Science (cond-mat.mtrl-sci)
29 pages (20 main article, 9 in supplementary Material, 1 table, 19 figures (10 in main article, 9 in supplementary Material)
Charge Order Driven Multiferroic Behaviour in Sr\(_4\)Fe\(_6\)O\(_{12}\): An \(\textit{Ab-initio}\) Study
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-05 20:00 EST
Arindam Sarkar, Hena Das, Prashant Singh, Aftab Alam
In this letter, we report the structural, electronic and ferroelectric properties of the layered mixed-valent transition-metal compound, Sr\(_{4}\)Fe\(_{6}\)O\(_{12}\) (SFO). We demonstrate how SFO undergoes a phase transition from a high-temperature (T) centrosymmetric tetragonal phase (\(P4_{2}/mnm\)) to a low-T polar orthorhombic phase (\(Pmn2_{1}\)). The transition is primarily driven by charge ordering at tetrahedral Fe-layer creating Fe\(^{3+}\) and Fe\(^{2+}\) cations between two edge sharing tetrahedra. This charge ordering induces electronic polarization, which is remarkably larger (3.5 times) in magnitude than ionic polarization and oppositely directed, giving a net polarization of 0.05 C/m\(^2\) which is comparable to the state-of-the-art rare-earth nickelets and manganite perovskites. The direction of structural distortion, governed by the polar mode irrep \(\Gamma_{5}^{-}\), depends sensitively on the type of magnetic ordering in the Fe-octahedral layer. Consequently, both the ionic and electronic polarization directions are influenced by magnetic ordering, suggesting the potential for multiferroic behavior with strong magneto-electric coupling in this material.
Strongly Correlated Electrons (cond-mat.str-el)
Direction-Dependent Conduction Polarity in Altermagnetic CrSb
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Banik Rai, Krishnendu Patra, Satyabrata Bera, Kakan Deb, Mintu Mondal, Priya Mahadevan, Nitesh Kumar
CrSb has recently gained immense attention as an altermagnetic candidate. This work reports on the experimental observation of direction-dependent conduction polarity (DDCP) in altermagnetic CrSb through Hall and Seebeck thermopower measurements. Conduction is dominated by holes along the c-axis and by electrons in the ab-plane of the hexagonal crystal of CrSb. Density functional theory (DFT) calculations indicate that DDCP in CrSb arises from a multicarrier mechanism, where electrons and holes living in distinct bands dominate conduction along different crystallographic directions. Furthermore, DFT predicts that DDCP exists within a narrow energy window near the Fermi level and is sensitive to small doping levels. This prediction is experimentally validated by the loss of DDCP in hole-doped Cr\(_{0.98}\)V\(_{0.02}\)Sb. These findings highlight the potential for tunable electronic behavior in CrSb, offering promising avenues for applications in devices that require both p-type and n-type functionalities within a single material.
Materials Science (cond-mat.mtrl-sci)
6 main figures, 8 SI figures
Multiscale micromagnetic / atomistic modeling of heat assisted magnetic recording
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Mohammed Gija, Alexey Dobrynin, Kevin McNeill, Mark Gubbins, Tim Mercer, Philip Bissell, Serban Lepadatu
Heat-assisted magnetic recording (HAMR) is a recent advancement in magnetic recording, allowing to significantly increase the areal density capability (ADC) of hard disk drives (HDDs) compared to the perpendicular magnetic recording (PMR) technology. This is enabled by high anisotropy FePt media, which needs to be heated through its Curie temperature (\(T_C\)) to facilitate magnetization reversal by an electromagnetic write pole. HAMR micromagnetic modeling is therefore challenging, as it needs to be performed in proximity to and above \(T_C\), where a ferromagnet has no spontaneous magnetization. An atomistic model is an optimal solution here, as it doesn't require any parameter renormalization or non-physical assumptions for modeling at any temperature. However, a full track atomistic recording model is extremely computationally expensive. Here we demonstrate a true multiscale HAMR modeling approach, combining atomistic spin dynamics modeling for high temperature regions and micromagnetic modeling for lower temperature regions, in a moving simulation window embedded within a long magnetic track. The advantages of this approach include natural emergence of \(T_C\) and anisotropy distributions of FePt grains. Efficient GPU optimization of the code provides very fast running times, with a 60~nm wide track of twenty-five 20~nm - long bits being recorded in several hours on a single GPU. The effects of realistic FePt L\(_{10}\) vs simple cubic crystal structure is discussed, with the latter providing further running time gains while keeping the advantages of the multiscale approach.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Femtosecond charge and spin dynamics in CoPt alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Martin Pavelka, Simon Marotzke, Ru-Pan Wang, Mohamed F. Elhanoty, Günter Brenner, Siarhei Dziarzhytski, Somnath Jana, W. Dieter Engel, Clemens v. Korff Schmising, Deeksha Gupta, Igor Vaskivskyi, Tim Amrhein, Nele Thielemann-Kühn, Martin Weinelt, Ronny Knut, Juliane Rönsch-Schulenberg, Evgeny Schneidmiller, Christian Schüßler-Langeheine, Martin Beye, Niko Pontius, Oscar Grånäs, Hermann A. Dürr
The use of advanced X-ray sources plays a key role in the study of dynamic processes in magnetically ordered materials. The progress in X-ray free electron lasers enables the direct and simultaneous observation of the femtosecond evolution of electron and spin systems through transient X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD), respectively. Such experiments allow us to resolve the response seen in the population of the spin-split valence states upon optical excitation. Here, we utilize circularly polarized ultrashort soft X-ray pulses from the new helical afterburner undulator at the free-electron laser FLASH in Hamburg to study the femtosecond dynamics of a laser-excited CoPt alloy at the Co \(L_{3}\) absorption edge. Despite employing a weaker electronic excitation level we find a comparable demagnetization for the Co \(3d\)-states in CoPt compared to previous measurements on CoPd. This is attributed to distinctly different orbital hybridization and spin-orbit coupling between \(3d\) and \(4d\) vs. \(3d\) and \(5d\) elements in the corresponding alloys and multilayers.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 3 figures
An altruistic resource-sharing mechanism for synchronization: The energy-speed-accuracy tradeoff
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-05 20:00 EST
Dongliang Zhang, Yuansheng Cao, Qi Ouyang, Yuhai Tu
Synchronization among a group of active agents is ubiquitous in nature. Although synchronization based on direct interactions between agents described by the Kuramoto model is well understood, the other general mechanism based on indirect interactions among agents sharing limited resources are less known. Here, we propose a minimal thermodynamically consistent model for the altruistic resource-sharing (ARS) mechanism wherein resources are needed for individual agent to advance but a more advanced agent has a lower competence to obtain resources. We show that while differential competence in ARS mechanism provides a negative feedback leading to synchronization it also breaks detailed balance and thus requires additional energy dissipation besides the cost of driving individual agents. By solving the model analytically, our study reveals a general tradeoff relation between the total energy dissipation rate and the two key performance measures of the system: average speed and synchronization accuracy. For a fixed dissipation rate, there is a distinct speed-accuracy Pareto front traversed by the scarcity of resources: scarcer resources lead to slower speed but more accurate synchronization. Increasing energy dissipation eases this tradeoff by pushing the speed-accuracy Pareto front outwards. The connections of our work to realistic biological systems such as the KaiABC system in cyanobacterial circadian clock and other theoretical results based on thermodynamic uncertainty relation are also discussed.
Statistical Mechanics (cond-mat.stat-mech), Biological Physics (physics.bio-ph)
main text 6 pages, 3 figures; SI 10 pages, 4 figures
From superconductivity to non-superconductivity in LiPdH: a first principle approach
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-05 20:00 EST
Zahra Alizadeh, Yue-Wen Fang, Ion Errea, M.R. Mohammadizadeh
The layered structure of LiPdH was theoretically suggested to be a superconductor as a result of its larger electron-phonon coupling constant compared to that of PdH. However, the experimental results reported contrary findings, with no trace of superconductivity. We study the electronic, vibrational, and superconducting properties of the ambient pressure tetragonal phase of LiPdH (\(P4/mmm\)) within first principles density functional theory methods, both in the harmonic and anharmonic approximations for the lattice dynamics, and conclude that it does not show any superconducting behavior. High-pressure crystal structure prediction calculations indicate that no structural transition is expected to occur under pressure up to 100 GPa in LiPdH. Our theoretical calculations demonstrate that increasing pressure reduces the density of states at the Fermi surface and consequently weakens electron-phonon interactions, leading to a further suppression of the superconducting critical temperature.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Benchmarking a magnon-scattering reservoir with modal and temporal multiplexing
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
Christopher Heins, Joo-Von Kim, Lukas Körber, Jürgen Fassbender, Helmut Schultheiss, Katrin Schultheiss
Physical reservoir computing has emerged as a powerful framework for exploiting the inherent nonlinear dynamics of physical systems to perform computational tasks. Recently, we presented the magnon-scattering reservoir, whose internal nodes are given by the fundamental wave-like excitations of ferromagnets called magnons. These excitations can be geometrically-quantized and, in response to an external stimulus, show transient nonlinear scattering dynamics that can be harnessed to perform memory and nonlinear transformation tasks. Here, we test a magnon-scattering reservoir in a single magnetic disk in the vortex state towards two key performance indicators for physical reservoir computing, the short-term memory and parity-check tasks. Using time-resolved Brillouin-light-scattering microscopy, we measure the evolution of the reservoir's spectral response to an input sequence consisting of random binary inputs encoded in microwave pulses with two distinct frequencies. Two different output spaces of the reservoir are defined, one based on the time-averaged frequency spectra and another based on temporal multiplexing. Our results demonstrate that the memory and nonlinear transformation capability do not depend on the chosen read-out scheme as long as the dimension of the output space is large enough to capture all nonlinear features provided by the magnon-magnon interactions. This further shows that solely the nonlinear magnons in the physical system, not the read-out, determine the reservoir's capacity.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Computational insights into Cobalt-based novel half-Heusler alloy for sustainable energy applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Sumit Kumar, Diwaker, Ashwani Kumar, Vivek, Arvind Sharma, Karan S. Vinayak, Shyam Lal Gupta
The quest for efficient and sustainable green energy solutions has led to a growing interest in half Heusler alloys, particularly for thermoelectric and spintronic applications. This study investigates the multifaceted nature of cobalt based half Heusler alloy, CoVAs, employing DFT with advanced computational techniques, such as the FLAPW method. The elastic, electronic, magnetic, thermodynamic, and optical properties of CoVAs are meticulously analyzed. Structural and mechanical evaluations reveal mechanical stability and brittleness under varying pressures. Electronic and magnetic properties are examined through band structure and DOS analysis, revealing a half metallic nature with a minority spin band gap. The total magnetic moment aligns with the Slater Pauling rule, further confirming ferromagnetism and half metallicity. Thermodynamic investigations, based on the quasi-harmonic Debye approximation, provide insights into temperature- and pressure dependent behavior, including thermal expansion, heat capacity, and Debye temperature, establishing CoVAs as a viable candidate for high temperature applications. Additionally, the optical properties underestimate its potential in optoelectronic applications due to high absorption in the UV region, showing a distinct absorption edge corresponding to the electronic band gap. Phonon dispersion relations reflect the stability of the alloy, and the figure of merit confirms the alloy's suitability for thermodynamics applications. The findings highlight the potential of CoVAs as a promising candidate for spintronic photovoltaic and optoelectronic applications, providing insights into its fundamental properties that could facilitate experimental synthesis and industrial implementation for green energy and advanced technological applications.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Anomalous Creep as a Precursor to Failure in Granular Materials
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-05 20:00 EST
Granular materials, composed of discrete solid grains, can be modeled as simple mechanical systems. However, these materials can undergo spontaneous slow deformation, or creep, even under small forces and while in apparent mechanical equilibrium; a phenomenon central to understanding soil mechanics and the behavior of earthquake faults. We show that creep in granular materials originates from frictional dynamics at the contact points between grains. We reveal that the stability of these materials is governed by the interplay between creep and aging at these frictional contacts. Near the yield threshold, the frictional interactions result in anomalously accelerating creep, eventually leading to the delayed failure of the fragile packing. This behavior may serve as an early warning signal for catastrophic events like earthquakes and landslides.
Soft Condensed Matter (cond-mat.soft)
Ultrafast laser synthesis of zeolites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Sezin Galioglu, Mehdi Hagverdiyev, Meryem M. Doğan, Özgün Yavuz, Ü. Seleme Nizam, Ghaith Makey, Aladin Choura, Mesut Laçin, Burcu Akata Kurç, Parviz Elahi, F. Ömer Ilday, Serim Ilday
Research has demonstrated that zeolite nucleation and growth can be controlled by fine-tuning chemical composition, temperature, and pressure, resulting in structures with diverse porosities and functionalities. Nevertheless, current energy delivery methods lack the finesse required to operate on the femto- and picosecond timescales of silica polymerisation and depolymerisation, limiting their ability to direct synthesis with high precision. To overcome this limitation, we introduce an ultrafast laser synthesis technique capable of delivering energy at these timescales with unprecedented spatiotemporal precision. Unlike conventional or emerging approaches, this method bypasses the need for specific temperature and pressure settings, as nucleation and growth are governed by dynamic phenomena arising from nonlinear light-matter interactions, such as convective flows, cavitation bubbles, plasma formation, and shock waves. These processes can be initiated, paused, and resumed within fractions of a second, effectively freezing structures at any stage of self-assembly. Using this approach, we traced the entire nucleation and growth pathway of laser-synthesized TPA-silicate-1 zeolites, from early oligomer formation to fully developed crystals. The unprecedented spatiotemporal control of this technique unlocks new avenues for manipulating reaction pathways and exploring the vast configurational space of zeolites.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Chemical Physics (physics.chem-ph)
main text, 6 figures, 4 video files, supplementary information
Spin filtration in a single-stranded antiferromagnetic helix with slowly varying disorder: Higher order electron hopping
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
Suparna Sarkar, Santanu K. Maiti, David Laroze
This work explores spin filtration in a helical magnetic system within a tight-binding framework, where neighboring magnetic moments are aligned antiparallel. The helix experiences a slowly-varying diagonal disorder, following a cosine form, which creates a finite energy mismatch between up and down spin channels. Unlike earlier studies that relied on external electric fields, this investigation demonstrates that disorder alone can achieve high spin filtration, even at low bias and high temperatures. Higher-order electron hopping in the helix leads to a non-uniform energy level distribution, facilitating favorable spin filtration, sometimes reaching \(100\%\). The interplay between higher-order hopping and atypical disorder may enable selective spin transmission through various antiferromagnetic helices, potentially opening new avenues for functional elements.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 10 figures (comments are welcome)
Flow rate from a vertical silo with a tilted orifice
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-05 20:00 EST
Ryan Kozlowski, Luis A. Pugnaloni
The flow of dry granular materials from silos is of great practical interest in industry and of theoretical import for understanding multiphase dynamics. Recent studies have demonstrated that one way to control the rate of flow from a silo is to tilt it. However, this may not be practical in many industrial applications. Here, we demonstrate in experiments of quasi-2D silo discharge of monodisperse grains that the flow rate can be modulated by rotating the orifice - through elevating and shifting one side of the base - instead of tilting the entire silo. We use high-speed image analysis to track the average motion of grains in the silo. We first show that the flow rate decreases with orifice angle, but that this decrease is not as strong as when a silo is tilted or when a lateral orifice is used. However, with the addition of a grain-sized ridge on each side of the orifice, the flow rate collapses with prior tilted-silo results. We then characterize the flow velocity of grains exiting the orifice and highlight key features of the stagnant zones and slip zones on each orifice side. Finally, we model our results based on these measurements, demonstrating the importance of horizontal creep along slip zones next to the orifice and the narrowest opening cross-section through which the material flows. These findings reveal a simple method for controlling both flow rate and direction, and highlight the importance of both dynamics within and geometry of the stagnant zones near the orifice.
Soft Condensed Matter (cond-mat.soft)
25 pages total: 2 pages with graphical abstract and highlights for preprint, 18 pages for main text, and 5 pages for supplemental materials. 16 figures in main text, 4 figures in supplemental materials. (Videos will be provided with Supplemental Materials upon peer-reviewed publication.)
Quasiparticle interference on the surface of Bi\(_{\mathbf{2}}\)Se\(_{\mathbf{3}}\) terminated (PbSe)\(_{\mathbf 5}\)(Bi\(_{\mathbf 2}\)Se\(_{\mathbf 3}\))\(_{\mathbf 6}\)
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
Mahasweta Bagchi, Philipp Rüßmann, Gustav Bihlmayer, Stefan Blügel, Yoichi Ando, Jens Brede
The family of topological superconductors derived from \(\mathrm{Bi}_{2}\mathrm{Se}_{3}\), \(\mathrm{Cu}_x(\mathrm{PbSe})_{5}(\mathrm{Bi}_{2}\mathrm{Se}_{3})_{6}\) is unique in its surface termination of a single quintuple layer (QL) of the topological insulator (TI) \(\mathrm{Bi}_{2}\mathrm{Se}_{3}\) on an ordinary insulator PbSe. Here, we report a combined scanning tunneling microscopy (STM) and density functional theory (DFT) characterization of the cleaved surface of the parent compound \((\mathrm{PbSe})_{5}(\mathrm{Bi}_{2}\mathrm{Se}_{3})_{6}\) (PSBS). Interestingly, the potential disorder due to the random distribution of native defects is only \(\Gamma \sim 4~\mathrm{meV}\), comparable to the smallest reported for TIs. Performing high-resolution quasiparticle interference imaging (QPI) near the Fermi energy (\(E-E_\mathrm{F} = -1~\mathrm{eV}\) to \(0.6~\mathrm{eV}\)) we reconstruct the dispersion relation of the dominant spectral feature and our \(\textit{ab initio}\) calculations show that this surface feature originates from two bands with Rashba-like splitting due to strong spin-orbit coupling and inversion symmetry breaking. Moreover, a small hexagonal distortion of the calculated Fermi surface is seen in the full momentum space distribution of the measured scattering data. Interestingly, the scattering pattern at lower energies transforms into a flower-like shape with suppressed intensity along the \(\overline{\Gamma K}\) direction. However, this effect is not due to the forbidden backscattering in the spin-momentum locked surface state in \(\mathrm{Bi}_{2}\mathrm{Se}_{3}\) but reflects the threefold symmetry of the scattering potential.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
12 pages with 12 figures
Photo-induced Dynamics and Momentum Distribution of Chiral Charge Density Waves in 1T-TiSe\(_{2}\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-05 20:00 EST
Qingzheng Qiu, Sae Hwan Chun, Jaeku Park, Dogeun Jang, Li Yue, Yeongkwan Kim, Yeojin Ahn, Mingi Jho, Kimoon Han, Xinyi Jiang, Qian Xiao, Tao Dong, Jia-Yi Ji, Nanlin Wang, Jeroen van den Brink, Jasper van Wezel, Yingying Peng
Exploring the photoinduced dynamics of chiral states offers promising avenues for advanced control of condensed matter systems. Photoinduced or photoenhanced chirality in 1T-TiSe\(_{2}\) has been suggested as a fascinating platform for optical manipulation of chiral states. However, the mechanisms underlying chirality training and its interplay with the charge density wave (CDW) phase remain elusive. Here, we use time-resolved X-ray diffraction (tr-XRD) with circularly polarized pump lasers to probe the photoinduced dynamics of chirality in 1T-TiSe\(_{2}\). We observe a notable ($\(20%) difference in CDW intensity suppression between left- and right-circularly polarized pumps. Additionally, we reveal momentum-resolved circular dichroism arising from domains of different chirality, providing a direct link between CDW and chirality. An immediate increase in CDW correlation length upon laser pumping is detected, suggesting the photoinduced expansion of chiral domains. These results both advance the potential of light-driven chirality by elucidating the mechanism driving chirality manipulation in TiSe\)_2$, and they demonstrate that tr-XRD with circularly polarized pumps is an effective tool for chirality detection in condensed matter systems.
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 4 figures
Composition Effects on Ni/Al Reactive Multilayers: A Comprehensive Study of Mechanical Properties, Reaction Dynamics and Phase Evolution
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Nensi Toncich, Fabian Schwarz, Rebecca A. Gallivan, Jemma Gillon, Ralph Spolenak
Ni/Al reactive multilayers are promising materials for applications requiring controlled local energy release and superior mechanical performance. This study systematically investigates the impact of compositional variations, ranging from 30 to 70 at.% Ni, and bilayer thicknesses (30 nm and 50 nm) on the mechanical properties and reaction dynamics of Ni/Al multilayers. Multilayers with varying Ni-to-Al ratios were fabricated and subjected to instrumented nanoindentation testing to evaluate hardness and elastic modulus. Combustion experiments, conducted on dogbone-shaped multilayers deposited onto silicon wafers with thermal barrier coatings, characterized the reaction front's speed, temperature, and the resulting phases. The findings revealed that composition variations within this range enable precise tuning of reaction speed and temperature without significant changes in mechanical properties, while deviations in modulus and hardness at higher nickel concentrations suggest microstructural influences. Notably, phase formation in Al-rich samples deviated from equilibrium predictions, highlighting the role of kinetic factors, such as diffusion and rapid quenching, in driving non-adiabatic processes during phase evolution. Molecular dynamics simulations provided complementary atomistic insights into mechanical responses and reaction kinetics, bridging experimental observations with theoretical predictions. This integrated approach advances the understanding of Ni/Al multilayers, offering a framework for optimizing their composition and structural design to achieve tailored performance for application-specific requirements.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
13 pages, 7 figures
Direct observation of the exciton polaron by serial femtosecond crystallography on single CsPbBr\(_3\) quantum dots
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Zhou Shen, Margarita Samoli, Onur Erdem, Johan Bielecki, Amit Kumar Samanta, Juncheng E, Armando Estillore, Chan Kim, Yoonhee Kim, Jayanath Koliyadu, Romain Letrun, Federico Locardi, Jannik Lübke, Abhishek Mall, Diogo Melo, Grant Mills, Safi Rafie-Zinedine, Adam Round, Tokushi Sato, Raphael de Wijn, Tamme Wollweber, Lena Worbs, Yulong Zhuang, Adrian P. Mancuso, Richard Bean, Henry N. Chapman, Jochen Küpper, Ivan Infante, Holger Lange, Zeger Hens, Kartik Ayyer
The outstanding opto-electronic properties of lead halide perovskites have been related to the formation of polarons. Nevertheless, the observation of the atomistic deformation brought about by one electron-hole pair in these materials has remained elusive. Here, we measure the diffraction patterns of single CsPbBr\(_3\) quantum dots (QDs) with and without resonant excitation in the single exciton limit using serial femtosecond crystallography (SFX). By reconstructing the 3D differential diffraction pattern, we observe small shifts of the Bragg peaks indicative of a crystal-wide deformation field. Building on DFT calculations, we show that these shifts are consistent with the lattice distortion induced by a delocalized electron and a localized hole, forming a mixed large/small exciton polaron. This result creates a clear picture of the polaronic deformation in CsPbBr\(_3\) QDs, highlights the exceptional sensitivity of SFX to lattice distortions in few-nanometer crystallites, and establishes an experimental platform for future studies of electron-lattice interactions.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Data Analysis, Statistics and Probability (physics.data-an)
Main: 12 pages, 5 figures; Supplemental: 21 pages, 11 figures
Electrical probe of spin-spiral order in quantum spin Hall/spin-spiral magnet van der Waals heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
Fedor Nigmatulin (1), Jose L. Lado (2), Zhipei Sun (1) ((1) QTF Centre of Excellence, Department of Electronics and Nanoengineering, Aalto University, (2) Department of Applied Physics, Aalto University)
Two-dimensional spin-spiral magnets provide promising building blocks for van der Waals heterostructures due to their tunable spin textures and potential for novel functionalities for quantum devices. However, due to its vanishing magnetization and two-dimensional nature, it is challenging to detect the existence of its noncollinear magnetization. Here, we show that a van der Waals junction based on a spin-spiral magnet and a quantum spin Hall insulator enables obtaining signatures of noncollinear magnetization directly from electrical measurements. Our strategy exploits the sensitivity of helical states to local breaking of time-reversal symmetry, enabling the detection of local magnetic orders even in the absence of net magnetization. We show that the combination of spin-spiral order and nonmagnetic disorder gives rise to scattering in the helical channels that can be directly associated with the spiral exchange coupling and residual nonmagnetic disorder strength. Our results show how electrical transport measurement provides a method to detect spin-spiral magnets by leveraging helical states in van der Waals heterostructures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Stable antiferroelectric phase in calcium-doped lead scandium tantalate
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Youri Nouchokgwe, Natalya S. Fedorova, Pranab Biswas, Veronika Kovacova, Ivana Gorican, Silvo Drmovsek, Binayak Mukherjee, Uros Prah, Guillaume F. Nataf, Torsten Granzow, Mael Guennou, Hana Ursic, Jorge Iniguez-Gonzalez, Emmanuel Defay
Antiferroelectrics are valuable dielectric materials, offering promise for both high energy storage and solid-state caloric cooling applications. However, few antiferroelectrics are known or available. Therefore, it is crucial to discover or design materials showing antiferroelectric behaviour. In this study, we fabricated highly ordered lead scandium tantalate ceramics doped with calcium. From calorimetry and polarization-electric field loops, we demonstrate the effect of calcium on the thermal properties and phase transition sequences of lead scandium tantalate. We identify an antiferroelectric phase appearing at temperatures intermediate between the ferroelectric and paraelectric phases, which becomes increasingly stable as the calcium concentration increases. These findings are supported by density functional theory calculations and Raman spectroscopy. Finally, we propose a phase diagram for calcium-doped lead scandium tantalate. Our results highlight the potential of stabilizing antiferroelectricity in ferroelectric perovskite materials through A-site doping.
Materials Science (cond-mat.mtrl-sci)
Neural network potential molecular dynamics simulations of (La,Ce,Pr,Nd)0.95(Mg,Zn,Pb,Cd,Ca,Sr,Ba)0.05F2.95
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Tysonite structure fluorides doped with divalent cations, represented by Ce0.95Ca0.05F2.95, are a class of good F- ion conductors together with fluorite-structured compounds. Computational understanding of the F- conduction process is difficult because of the complicated interactions between three symmetrically distinct F sites and the experimentally observed change in the F diffusion mechanism slightly above room temperature, effectively making first principles molecular dynamics (FP-MD) simulations, which are often conducted well above the transition temperature, useless when analyzing behavior below the transition point. Neural network potential (NNP) MD simulations showed that the F diffusion coefficient is higher when the divalent dopant cation size is similar to the trivalent cation size. The diffusion behavior of F in different sites changes at roughly 500 K in Ce0.95Ca0.05F2.95 because only the F1 site sublattice contributes to F diffusion below this temperature but the remaining F2 and F3 sublattices becomes gradually active above this temperature. The paradox of higher diffusion coefficients in CeF3-based compounds than similar LaF3-based compounds even though the lattice parameters are larger in the latter may be caused by a shallower potential of Ce and F in CeF3 compared to the LaF3 counterparts.
Materials Science (cond-mat.mtrl-sci)
J. Phys. Chem. B 2024,128,49,12171
Electric-Field Driven Nuclear Dynamics of Liquids and Solids from a Multi-Valued Machine-Learned Dipolar Model
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Elia Stocco, Christian Carbogno, Mariana Rossi
The driving of vibrational motion by external electric fields is a topic of continued interest, due to the possibility of assessing new or metastable material phases with desirable properties. Here, we combine ab initio molecular dynamics within the electric-dipole approximation with machine-learning neural networks (NNs) to develop a general, efficient and accurate method to perform electric-field-driven nuclear dynamics for molecules, solids, and liquids. We train equivariant and autodifferentiable NNs for the interatomic potential and the dipole, modifying the prediction target to account for the multi-valued nature of the latter in periodic systems. We showcase the method by addressing property modifications induced by electric field interactions in a polar liquid and a polar solid from nanosecond-long molecular dynamics simulations with quantum-mechanical accuracy. For liquid water, we present a calculation of the dielectric function in the GHz to THz range and the electrofreezing transition, showing that nuclear quantum effects enhance this phenomenon. For the ferroelectric perovskite LiNbO3, we simulate the ferroelectric to paraelectric phase transition and the non-equilibrium dynamics of driven phonon modes related to the polarization switching mechanisms, showing that a full polarization switch is not achieved in the simulations.
Materials Science (cond-mat.mtrl-sci)
Hydrogen liquid-liquid transition from first principles and machine learning
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-05 20:00 EST
Giacomo Tenti, Bastian Jäckl, Kousuke Nakano, Matthias Rupp, Michele Casula
The molecular-to-atomic liquid-liquid transition (LLT) in high-pressure hydrogen is a fundamental topic touching domains from planetary science to materials modeling. Yet, the nature of the LLT is still under debate. To resolve it, numerical simulations must cover length and time scales spanning several orders of magnitude. We overcome these size and time limitations by constructing a fast and accurate machine-learning interatomic potential (MLIP) built on the MACE neural network architecture. The MLIP is trained on Perdew-Burke-Ernzerhof (PBE) density functional calculations and uses a modified loss function correcting for an energy bias in the molecular phase. Classical and path-integral molecular dynamics driven by this MLIP show that the LLT is always supercritical above the melting temperature. The position of the corresponding Widom line agrees with previous ab initio PBE calculations, which in contrast predicted a first-order LLT. According to our calculations, the crossover line becomes a first-order transition only inside the molecular crystal region. These results call for a reconsideration of the LLT picture previously drawn.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Materials Science (cond-mat.mtrl-sci)
Solvers for Large-Scale Electronic Structure Theory: ELPA and ELSI
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Petr Karpov, Andreas Marek, Tobias Melson, Alexander Pöppl, Victor Wen-zhe Yu, Ben Hourahine, Alberto Garcia, William Dawson, Yi Yao, William Huhn, Jonathan Moussa, Sam Hall, Reinhard Maurer, Uthpala Herath, Konstantin Lion, Sebastian Kokott, Volker Blum
In this contribution, we give an overview of the ELPA library and ELSI interface, which are crucial elements for large-scale electronic structure calculations in FHI-aims. ELPA is a key solver library that provides efficient solutions for both standard and generalized eigenproblems, which are central to the Kohn-Sham formalism in density functional theory (DFT). It supports CPU and GPU architectures, with full support for NVIDIA and AMD GPUs, and ongoing development for Intel GPUs. Here we also report the results of recent optimizations, leading to significant improvements in GPU performance for the generalized eigenproblem. ELSI is an open-source software interface layer that creates a well-defined connection between "user" electronic structure codes and "solver" libraries for the Kohn-Sham problem, abstracting the step between Hamilton and overlap matrices (as input to ELSI and the respective solvers) and eigenvalues and eigenvectors or density matrix solutions (as output to be passed back to the "user" electronic structure code). In addition to ELPA, ELSI supports solvers including LAPACK and MAGMA, the PEXSI and NTPoly libraries (which bypass an explicit eigenvalue solution), and several others.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Contribution to the upcoming Roadmap for Advancements of the FHI-aims Software Package
Hydroelastic scattering and trapping of microswimmers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-05 20:00 EST
Sagnik Garai, Ursy Makanga, Akhil Varma, Christina Kurzthaler
Deformable boundaries are omnipresent in the habitats of swimming microorganisms, leading to intricate hydroelastic couplings. Employing a perturbation theory, valid for small deformations, we study the swimming dynamics of pushers and pullers near instantaneously deforming boundaries, endowed with a bending rigidity and surface tension. Our results reveal that pushers can both reorient away from the boundary, leading to overall hydroelastic scattering, or become trapped by the boundary, akin to the enhanced trapping found for pullers. These findings demonstrate that the complex hydroelastic interactions can generate behaviors that are in striking contrast to swimming near planar walls.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Fluctuations of stochastic charged cellular automata
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-05 20:00 EST
Žiga Krajnik, Katja Klobas, Bruno Bertini, Tomaž Prosen
We obtain the exact full counting statistics of a cellular automaton with freely propagating vacancies and charged particles that are stochastically scattered or transmitted upon collision by identifying the problem as a colored stochastic six-vertex model with one inert color. Typical charge current fluctuation at vanishing net charge follow a one-parameter distribution that interpolated between the distribution of the charged single-file class in the limit of pure reflection and a Gaussian distribution in the limit of pure transmission.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
35 pages, comments welcome
Automated tuning and characterization of a single-electron transistor charge sensor
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-05 20:00 EST
Andrija Paurevic, Ali Sakr, Tanmay Joshi, Dennis van der Bovenkamp, Quim T. Nicolau, Floris A. Zwanenburg, Jonathan Baugh
We present an automated protocol for tuning single-electron transistors (SETs) or single-hole transistors (SHTs) to operate as precise charge sensors. Using minimal device-specific information, the protocol performs measurements to enable the selection and ranking of high-sensitivity operating points. It also characterizes key device parameters, such as dot radius and gate lever arms, through acquisition and analysis of Coulomb diamonds. Demonstration on an accumulation-mode silicon SET at 1.5 K highlights its potential in the 1-2 K range for "hot" spin qubits in scalable quantum computing systems. This approach significantly reduces the tuning time compared to manual methods, with future improvements aimed at faster runtimes and dynamic feedback for robustness to charge fluctuations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
3 figures
Fluctuation Dissipation Relations for the Non-Reciprocal Cahn-Hilliard Model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-05 20:00 EST
Martin Kjøllesdal Johnsrud, Ramin Golestanian
Recent results demonstrate how deviations from equilibrium fluctuation-dissipation theorem can be quantified for active field theories by deriving exact fluctuations dissipation relations that involve the entropy production [M. K. Johnsrud and R. Golestanian, arXiv:2409.14977]. Here we develop and employ diagrammatic tools to perform perturbative calculations for a paradigmatic active field theory, the Non-Reciprocal Cahn-Hilliard (NRCH) model. We obtain analytical results, which serve as an illustration of how to implement the recently developed framework to active field theories, and help to illuminate the specific non-equilibrium characteristics of the NRCH field theory.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
arXiv admin note: substantial text overlap with arXiv:2409.14977
Optimizing oil-water separation using fractal surfaces
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-05 20:00 EST
Cristina Gavazzoni, Davi Lazzari, Iara Patrícia da Silva Ramos, Carolina Brito
Oil has become a prevalent global pollutant, stimulating the research to improve the techniques to separate oil from water. Materials with special wetting properties - primarily those that repel water while attracting oil - have been proposed as suitable candidates for this task. However, one limitation in developing efficient substrates is the limited available volume for oil absorption. In this study we investigate the efficacy of disordered fractal materials in addressing this challenge, leveraging their unique wetting properties. Using a combination of a continuous model and Monte Carlo simulations, we characterize the hydrophobicity and oleophilicity of substrates created through ballistic deposition (BD). Our results demonstrate that these materials exhibit high contact angles for water, confirming their hydrophobic nature, while allowing significant oil penetration, indicative of oleophilic behavior. The available free volume within the substrates vary from \(60\%\) to \(90\%\) of the total volume of the substrate depending on some parameters of the BD. By combining their water and oil wetting properties with a high availability of volume, the fractal substrates analyzed in this work achieve an efficiency in separating oil from water of nearly \(98\%\), which is significantly higher compared to a micro-pillared surfaces made from the same material but lacking a fractal design.
Statistical Mechanics (cond-mat.stat-mech)
7 pages, 5 figures. arXiv admin note: text overlap with arXiv:2012.11562
J. Chem. Phys. 28 January 2025; 162 (4): 044702
Influence of the growth temperature and annealing on the optical properties of {CdO/ZnO}30 superlattices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
E. Przeździecka, A. Lysak, A. Adhikari, M. Stachowicz, A. Wierzbicka, R. Jakiela, K. Zeinab, P. Sybilski, A. Kozanecki
Optical properties of the short period {CdO/ZnO} superlattices grown by plasma assisted MBE were analyzed. The superlattice (SLs) structures were successfully obtained at different growth temperatures from 360 to 550 °C. Interestingly, the growth temperature of the SLs influences quality of multilayers and also optical properties of these structures. After annealing at 900°C by rapid thermal method various defect luminescence located at different energetic positions , were detected, and intensity of luminescence strongly depends on applied growth temperature.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Journal of Luminescence Volume 269, May 2024, 120481
The Classical-to-Quantum Crossover in strain-induced ferroelectric transition in SrTiO\(_3\) membranes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-05 20:00 EST
Jiarui Li, Yonghun Lee, Yongseong Choi, Jong-Woo Kim, Paul Thompson, Kevin J. Crust, Ruijuan Xu, Harold Y. Hwang, Philip J. Ryan, Wei-Sheng Lee
Mechanical strain presents an effective control over symmetry-breaking phase transitions. In quantum paralelectric SrTiO3, strain can induce the ferroelectric transition via modification of local Ti potential landscape. However, brittle bulk materials can only withstand limited strain range (~0.1%). Taking advantage of nanoscopically-thin freestanding membranes, we demonstrated in-situ strain-induced reversible ferroelectric transition in a single freestanding SrTiO3 membranes. We measure the ferroelectric order by detecting the local anisotropy of the Ti 3d orbital using X-ray linear dichroism at the Ti-K pre-edge, while the strain is determined by X-ray diffraction. With reduced thickness, the SrTiO3 membranes remain elastic with >1% tensile strain cycles. A robust displacive ferroelectricity appears beyond a temperature-dependent critical strain. Interestingly, we discover a crossover from a classical ferroelectric transition to a quantum regime at low temperatures, which enhances strain-induced ferroelectricity. Our results offer a new opportunities to strain engineer functional properties in low dimensional quantum materials and provide new insights into the role of the ferroelectric fluctuations in quantum paraelectric SrTiO3.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
19 pages, 4 figures