CMP Journal 2025-02-13
Statistics
Science: 16
Physical Review Letters: 2
Physical Review X: 2
Review of Modern Physics: 1
arXiv: 68
Science
Engineering grain boundaries in monolayer molybdenum disulfide for efficient water-ion separation
Research Article | Membranes | 2025-02-13 01:59 EST
Jie Shen, Areej Aljarb, Yichen Cai, Xing Liu, Jiacheng Min, Yingge Wang, Qingxiao Wang, Chenhui Zhang, Cailing Chen, Mariam Hakami, Jui-Han Fu, Hui Zhang, Guanxing Li, Xiaoqian Wang, Zhuo Chen, Jiaqiang Li, Xinglong Dong, Kaimin Shih, Kuo-Wei Huang, Vincent Tung, Guosheng Shi, Ingo Pinnau, Lain-Jong Li, Yu Han
Two-dimensional (2D) materials have long been considered as ideal platforms for developing separation membranes. However, it is difficult to generate uniform subnanometer pores over large areas on 2D materials. We report that the well-defined eight-membered ring (8-MR) pores, typically formed at the boundaries of two antiparallel grains of monolayer molybdenum disulfide (MoS2), can serve as molecular sieves for efficient water-ion separation. The density of grain boundaries and, consequently, the number of 8-MR pores can be tuned by regulating the grain size. Optimized MoS2 membranes outperformed the state-of-the-art membranes in forward osmosis tests by demonstrating both ultrahigh water/sodium chloride selectivity and exceptional water permeance. Creating precise pore structures on atomically thin films through grain boundary engineering presents a promising route for producing membranes suitable for various applications.
Thalamic opioids from POMC satiety neurons switch on sugar appetite
Research Article | Neuroscience | 2025-02-13 01:59 EST
Marielle Minère, Hannah Wilhelms, Bojana Kuzmanovic, Sofia Lundh, Debora Fusca, Alina Claßen, Stav Shtiglitz, Yael Prilutski, Itay Talpir, Lin Tian, Brigitte Kieffer, Jon Davis, Peter Kloppenburg, Marc Tittgemeyer, Yoav Livneh, Henning Fenselau
High sugar-containing foods are readily consumed, even after meals and beyond fullness sensation (e.g., as desserts). Although reward-driven processing of palatable foods can promote overeating, the neurobiological mechanisms that underlie the selective appetite for sugar in states of satiety remain unclear. Hypothalamic pro-opiomelanocortin (POMC) neurons are principal regulators of satiety because they decrease food intake through excitatory melanocortin neuropeptides. We discovered that POMC neurons not only promote satiety in fed conditions but concomitantly switch on sugar appetite, which drives overconsumption. POMC neuron projections to the paraventricular thalamus selectively inhibited postsynaptic neurons through mu-opioid receptor signaling. This opioid circuit was strongly activated during sugar consumption, which was most notable in satiety states. Correspondingly, inhibiting its activity diminished high-sugar diet intake in sated mice.
Elephant seals as ecosystem sentinels for the northeast Pacific Ocean twilight zone
Research Article | Marine conservation | 2025-02-13 01:59 EST
Roxanne S. Beltran, Allison R. Payne, A. Marm Kilpatrick, Conner M. Hale, Madison Reed, Elliott L. Hazen, Steven J. Bograd, Joffrey Jouma'a, Patrick W. Robinson, Emma Houle, Wade Matern, Alea Sabah, Kathryn Lewis, Samantha Sebandal, Allison Coughlin, Natalia Valdes Heredia, Francesca Penny, Sophie Rose Dalrymple, Heather Penny, Meghan Sherrier, Ben Peterson, Joanne Reiter, Burney J. Le Boeuf, Daniel P. Costa
The open ocean twilight zone holds most of the global fish biomass but is poorly understood owing to difficulties of measuring subsurface ecosystem processes at scale. We demonstrate that a wide-ranging carnivore--the northern elephant seal--can serve as an ecosystem sentinel for the twilight zone. We link ocean basin-scale foraging success with oceanographic indices to estimate twilight zone fish abundance five decades into the past, and into the future. We discovered that a small variation in maternal foraging success amplified into larger changes in offspring body mass and enormous variation in first-year survival and recruitment. Worsening oceanographic conditions could shift predator population trajectories from current growth to sharp declines. As ocean integrators, wide-ranging predators could reveal impacts of future anthropogenic change on open ocean ecosystems.
Ultrastable supported oxygen evolution electrocatalyst formed by ripening-induced embedding
Research Article | Electrochemistry | 2025-02-13 01:59 EST
Wenjuan Shi, Tonghao Shen, Chengkun Xing, Kai Sun, Qisheng Yan, Wenzhe Niu, Xiao Yang, Jingjing Li, Chenyang Wei, Ruijie Wang, Shuqing Fu, Yong Yang, Liangyao Xue, Junfeng Chen, Shiwen Cui, Xiaoyue Hu, Ke Xie, Xin Xu, Sai Duan, Yifei Xu, Bo Zhang
The future deployment of terawatt-scale proton exchange membrane water electrolyzer (PEMWE) technology necessitates development of an efficient oxygen evolution catalyst with low cost and long lifetime. Currently, the stability of the most active iridium (Ir) catalysts is impaired by dissolution, redeposition, detachment, and agglomeration of Ir species. Here we present a ripening-induced embedding strategy that securely embeds the Ir catalyst in a cerium oxide support. Cryogenic electron tomography and all-atom kinetic Monte Carlo simulations reveal that synchronizing the growth rate of the support with the nucleation rate of Ir, regulated by sonication, is pivotal for successful synthesis. A PEMWE using this catalyst achieves a cell voltage of 1.72 volts at a current density of 3 amperes per square centimeter with an Ir loading of just 0.3 milligrams per square centimeter and a voltage degradation rate of 1.33 microvolts per hour, as demonstrated by a 6000-hour accelerated aging test.
Good plasmons in a bad metal
Research Article | Quantum materials | 2025-02-13 01:59 EST
Francesco L. Ruta, Yinming Shao, Swagata Acharya, Anqi Mu, Na Hyun Jo, Sae Hee Ryu, Daria Balatsky, Yifan Su, Dimitar Pashov, Brian S. Y. Kim, Mikhail I. Katsnelson, James G. Analytis, Eli Rotenberg, Andrew J. Millis, Mark van Schilfgaarde, D. N. Basov
Correlated metals may exhibit unusually high resistivity that increases linearly in temperature, breaking through the Mott-Ioffe-Regel bound, above which coherent quasiparticles are destroyed. The fate of collective charge excitations, or plasmons, in these systems is a subject of debate. Several studies have suggested that plasmons are overdamped, whereas other studies have detected propagating plasmons. In this work, we present direct nano-optical images of low-loss hyperbolic plasmon polaritons (HPPs) in the correlated van der Waals metal MoOCl2. HPPs are plasmon-photon modes that waveguide through extremely anisotropic media and are remarkably long-lived in MoOCl2. Photoemission data presented here reveal a highly anisotropic Fermi surface, reconstructed and made partly incoherent, likely through electronic interactions as explained by many-body theory. HPPs remain long-lived despite this, revealing previously unseen imprints of many-body effects on plasmonic collective modes.
Depth-dependent seismic sensing of groundwater recovery from the atmospheric-river storms of 2023
Research Article | Geophysics | 2025-02-13 01:59 EST
Shujuan Mao, William L. Ellsworth, Yujie Zheng, Gregory C. Beroza
In early 2023, a series of intense atmospheric-river storms eased California's historic drought, yet the spatiotemporal extent of groundwater recovery remains poorly understood. We tracked two-decadal changes in groundwater in Greater Los Angeles using seismic ambient-field interferometry. The derived seismic hydrographs reveal distinct expressions of groundwater and surficial water droughts: Whereas surface and near-surface water storage nearly fully recovered in the epic wet season of 2023, only about 25% of the groundwater lost since 2006 was restored. On a decadal scale, we find substantial depletion in aquifers below 50-meter depth, with only limited storm-related recovery. Our analysis underscores the need to monitor deep aquifers for a more complete assessment of total water deficits, using high-resolution tools such as seismic sensing.
RNA polymerase II at histone genes predicts outcome in human cancer
Research Article | Cancer | 2025-02-13 01:59 EST
Steven Henikoff, Ye Zheng, Ronald M. Paranal, Yiling Xu, Jacob E. Greene, Jorja G. Henikoff, Zachary R. Russell, Frank Szulzewsky, H. Nayanga Thirimanne, Sita Kugel, Eric C. Holland, Kami Ahmad
Genome-wide hypertranscription is common in human cancer and predicts poor prognosis. To understand how hypertranscription might drive cancer, we applied our formalin-fixed paraffin-embedded (FFPE)-cleavage under targeted accessible chromatin method for mapping RNA polymerase II (RNAPII) genome-wide in FFPE sections. We demonstrate global RNAPII elevations in mouse gliomas and assorted human tumors in small clinical samples and discover regional elevations corresponding to de novo HER2 amplifications punctuated by likely selective sweeps. RNAPII occupancy at S-phase-dependent histone genes correlated with WHO grade in meningiomas, accurately predicted rapid recurrence, and corresponded to whole-arm chromosome losses. Elevated RNAPII at histone genes in meningiomas and diverse breast cancers is consistent with histone production being rate-limiting for S-phase progression and histone gene hypertranscription driving overproliferation and aneuploidy in cancer, with general implications for precision oncology.
Selective chemical looping combustion of acetylene in ethylene-rich streams
Research Article | Catalysis | 2025-02-13 01:59 EST
Matthew Jacob, Huy Nguyen, Rishi Raj, Javier Garcia-Barriocanal, Jiyun Hong, Jorge E. Perez-Aguilar, Adam S. Hoffman, K. Andre Mkhoyan, Simon R. Bare, Matthew Neurock, Aditya Bhan
The requirement for C2H2 concentrations below 2 parts per million (ppm) in gas streams for C2H4 polymerization necessitates its semihydrogenation to C2H4. We demonstrate selective chemical looping combustion of C2H2 in C2H4-rich streams by Bi2O3 as an alternative catalytic pathway to reduce C2H2 concentration below 2 ppm. Bi2O3 combusts C2H2 with a first-order rate constant that is 3000 times greater than the rate constant for C2H4 combustion. In successive redox cycles, the lattice O of Bi2O3 can be fully replenished without discernible changes in local Bi coordination or C2H2 combustion selectivity. Heterolytic activation of C-H bonds across Bi-O sites and the higher acidity of C2H2 results in lower barriers for C2H2 activation than C2H4, enabling selective catalytic hydrocarbon combustion leveraging differences in molecular deprotonation energies.
Thermal catalytic reforming for hydrogen production with zero CO2 emission
Research Article | Catalysis | 2025-02-13 01:59 EST
Mi Peng, Yuzhen Ge, Rui Gao, Jie Yang, Aowen Li, Zhiheng Xie, Qiaolin Yu, Jie Zhang, Hiroyuki Asakura, Hui Zhang, Zhi Liu, Qi Zhang, Jin Deng, Jihan Zhou, Wu Zhou, Graham J. Hutchings, Ding Ma
Carbon-neutral hydrogen production is of key importance for the chemical industry of the future. We demonstrate a new thermal catalytic route for the partial reforming of ethanol into hydrogen and acetic acid with near-zero carbon dioxide emissions. This reaction is enabled by a catalyst containing a high density of atomic Pt1 and Ir1 species supported on a reactive alpha-molybdenum carbide substrate, achieving a hydrogen production rate of 331.3 millimoles of hydrogen per gram catalyst per hour and an acetic acid selectivity of 84.5% at 270°C, and is therefore more energy-efficient compared with standard reforming. Techno-economic analysis of partial ethanol reforming demonstrates the potential profitability for operation at an industrial scale, presenting the opportunity to produce hydrogen and acetic acid with a substantially reduced carbon dioxide footprint.
Evolutionary convergence of sensory circuits in the pallium of amniotes
Research Article | Brain evolution | 2025-02-14 03:00 EST
Eneritz Rueda-Alaña, Rodrigo Senovilla-Ganzo, Marco Grillo, Enrique Vázquez, Sergio Marco-Salas, Tatiana Gallego-Flores, Aitor Ordeñana-Manso, Artemis Ftara, Laura Escobar, Alberto Benguría, Ana Quintas, Ana Dopazo, Miriam Rábano, María dM Vivanco, Ana María Aransay, Daniel Garrigos, Ángel Toval, José Luis Ferrán, Mats Nilsson, Juan Manuel Encinas-Pérez, Maurizio De Pittà, Fernando García-Moreno
The amniote pallium contains sensory circuits that are structurally and functionally equivalent, yet their evolutionary relationship remains unresolved. We used birthdating analysis, single-cell RNA and spatial transcriptomics, and mathematical modeling to compare the development and evolution of known pallial circuits across birds (chick), lizards (gecko), and mammals (mouse). We reveal that neurons within these circuits' stations are generated at varying developmental times and brain regions across species and found an early developmental divergence in the transcriptomic progression of glutamatergic neurons. Our research highlights developmental distinctions and functional similarities in the sensory circuit between birds and mammals, suggesting the convergence of high-order sensory processing across amniote lineages.
Developmental origins and evolution of pallial cell types and structures in birds
Research Article | Brain evolution | 2025-02-14 03:00 EST
Bastienne Zaremba, Amir Fallahshahroudi, Céline Schneider, Julia Schmidt, Ioannis Sarropoulos, Evgeny Leushkin, Bianka Berki, Enya Van Poucke, Per Jensen, Rodrigo Senovilla-Ganzo, Francisca Hervas-Sotomayor, Nils Trost, Francesco Lamanna, Mari Sepp, Fernando García-Moreno, Henrik Kaessmann
Innovations in the pallium likely facilitated the evolution of advanced cognitive abilities in birds. We therefore scrutinized its cellular composition and evolution using cell type atlases from chicken, mouse, and nonavian reptiles. We found that the avian pallium shares most inhibitory neuron types with other amniotes. Whereas excitatory neuron types in amniote hippocampal regions show evolutionary conservation, those in other pallial regions have diverged. Neurons in the avian mesopallium display gene expression profiles akin to the mammalian claustrum and deep cortical layers, while certain nidopallial cell types resemble neurons in the piriform cortex. Lastly, we observed substantial gene expression convergence between the dorsally located hyperpallium and ventrally located nidopallium during late development, suggesting that topological location does not always dictate gene expression programs determining functional properties in the adult avian pallium.
Enhancer-driven cell type comparison reveals similarities between the mammalian and bird pallium
Research Article | Brain evolution | 2025-02-14 03:00 EST
Nikolai Hecker, Niklas Kempynck, David Mauduit, Darina Abaffyová, Roel Vandepoel, Sam Dieltiens, Lars Borm, Ioannis Sarropoulos, Carmen Bravo González-Blas, Julie De Man, Kristofer Davie, Elke Leysen, Jeroen Vandensteen, Rani Moors, Gert Hulselmans, Lynette Lim, Joris De Wit, Valerie Christiaens, Suresh Poovathingal, Stein Aerts
Combinations of transcription factors govern the identity of cell types, which is reflected by genomic enhancer codes. We used deep learning to characterize these enhancer codes and devised three metrics to compare cell types in the telencephalon across amniotes. To this end, we generated single-cell multiome and spatially resolved transcriptomics data of the chicken telencephalon. Enhancer codes of orthologous nonneuronal and γ-aminobutyric acid-mediated (GABAergic) cell types show a high degree of similarity across amniotes, whereas excitatory neurons of the mammalian neocortex and avian pallium exhibit varying degrees of similarity. Enhancer codes of avian mesopallial neurons are most similar to those of mammalian deep-layer neurons. With this study, we present generally applicable deep learning approaches to characterize and compare cell types on the basis of genomic regulatory sequences.
KLF2 maintains lineage fidelity and suppresses CD8 T cell exhaustion during acute LCMV infection
Research Article | Immunology | 2025-02-14 03:00 EST
Eric Fagerberg, John Attanasio, Christine Dien, Jaiveer Singh, Emily A. Kessler, Leena Abdullah, Jian Shen, Brian G. Hunt, Kelli A. Connolly, Edward De Brouwer, Jiaming He, Nivedita R. Iyer, Jessica Buck, Emily R. Borr, Martina Damo, Gena G. Foster, Josephine R. Giles, Yina H. Huang, John S. Tsang, Smita Krishnaswamy, Weiguo Cui, Nikhil S. Joshi
Naïve CD8 T cells have the potential to differentiate into a spectrum of functional states during an immune response. How these developmental decisions are made and what mechanisms exist to suppress differentiation toward alternative fates remains unclear. We employed in vivo CRISPR-Cas9-based perturbation sequencing to assess the role of ~40 transcription factors (TFs) and epigenetic modulators in T cell fate decisions. Unexpectedly, we found that knockout of the TF Klf2 resulted in aberrant differentiation to exhausted-like CD8 T cells during acute infection. KLF2 was required to suppress the exhaustion-promoting TF TOX and to enable the TF TBET to drive effector differentiation. KLF2 was also necessary to maintain a polyfunctional tumor-specific progenitor state. Thus, KLF2 provides effector CD8 T cell lineage fidelity and suppresses the exhaustion program.
Variability of flowing stream network length across the US
Research Article | Hydrology | 2025-02-13 01:59 EST
Jeff P. Prancevic, Hansjörg Seybold, James W. Kirchner
The aggregate length of flowing streams in a drainage network lengthens and shortens as landscapes become wetter and drier. However, direct measurements of stream network variability have been limited to a handful of small drainage basins. We estimated the variability of stream network length for 14,765 gauged basins across the contiguous United States using measured streamflow distributions and topography-based estimates of how sensitive each stream network is to changing landscape wetness (the network's elasticity). We find that the median US stream network is five times longer during annual high-flow conditions than during annual low-flow conditions. Stream networks are more dynamic in some regions than in others, driven by regional differences in both hydroclimatology and the networks' elasticity in response to hydroclimatic forcing.
Conformational ensembles reveal the origins of serine protease catalysis
Research Article | Enzymology | 2025-02-14 03:00 EST
Siyuan Du, Rachael C. Kretsch, Jacob Parres-Gold, Elisa Pieri, Vinícius Wilian D. Cruzeiro, Mingning Zhu, Margaux M. Pinney, Filip Yabukarski, Jason P. Schwans, Todd J. Martínez, Daniel Herschlag
Enzymes exist in ensembles of states that encode the energetics underlying their catalysis. Conformational ensembles built from 1231 structures of 17 serine proteases revealed atomic-level changes across their reaction states. By comparing the enzymatic and solution reaction, we identified molecular features that provide catalysis and quantified their energetic contributions to catalysis. Serine proteases precisely position their reactants in destabilized conformers, creating a downhill energetic gradient that selectively favors the motions required for reaction while limiting off-pathway conformational states. The same catalytic features have repeatedly evolved in proteases and additional enzymes across multiple distinct structural folds. Our ensemble-function analyses revealed previously unknown catalytic features, provided quantitative models based on simple physical and chemical principles, and identified motifs recurrent in nature that may inspire enzyme design.
Neuroevolution insights into biological neural computation
Review | Neuroscience | 2025-02-14 03:00 EST
Risto Miikkulainen
This article reviews existing work and future opportunities in neuroevolution, an area of machine learning in which evolutionary optimization methods such as genetic algorithms are used to construct neural networks to achieve desired behavior. The article takes a neuroscience perspective, identifying where neuroevolution can lead to insights about the structure, function, and developmental and evolutionary origins of biological neural circuitry that can be studied in further neuroscience experiments. It proposes optimization under environmental constraints as a unifying theme and suggests the evolution of language as a grand challenge whose time may have come.
Physical Review Letters
Quantumlike Product States Constructed from Classical Networks
Research article | Complex systems | 2025-02-13 05:00 EST
Gregory D. Scholes and Graziano Amati
A one-to-one map between the product basis of quantum states and eigenstates of a classical-network-based construction could be used to mimic quantumlike product states.
Phys. Rev. Lett. 134, 060202 (2025)
Complex systems, Quantum correlations, foundations & formalism, Quantum information theory, Quantum superposition
Unveiling Resilient Superconducting Fluctuations in Atomically Thin \({\mathrm{NbSe}}_{2}\) through Higgs Mode Spectroscopy
Research article | Superconductivity | 2025-02-13 05:00 EST
Yu Du, Gan Liu, Wei Ruan, Zhi Fang, Kenji Watanabe, Takashi Taniguchi, Ronghua Liu, Jian-Xin Li, and Xiaoxiang Xi
An enigmatic and anomalous metallic state turns out to be intrinsic rather than a consequence of crystalline defects.
Phys. Rev. Lett. 134, 066002 (2025)
Superconductivity, 2-dimensional systems, Raman spectroscopy, Resistivity measurements
Physical Review X
Imaging Orbital Vortex Lines in Three-Dimensional Momentum Space
Research article | Electronic structure | 2025-02-13 05:00 EST
T. Figgemeier, M. Ünzelmann, P. Eck, J. Schusser, L. Crippa, J. N. Neu, B. Geldiyev, P. Kagerer, J. Buck, M. Kalläne, M. Hoesch, K. Rossnagel, T. Siegrist, L.-K. Lim, R. Moessner, G. Sangiovanni, D. Di Sante, F. Reinert, and H. Bentmann
Real-space quantum vortices are key to many phenomena in modern physics. New experiments provide the first proof of vortices in momentum space, raising the prospect of exploring novel orbitronic phenomena.
Phys. Rev. X 15, 011032 (2025)
Electronic structure, Topological materials, Angle-resolved photoemission spectroscopy
Valley Polarization of Landau Levels in the ZrSiS Surface Band Driven by Residual Strain
Research article | Landau levels | 2025-02-13 05:00 EST
Christopher J. Butler, Masayuki Murase, Shunki Sawada, Ming-Chun Jiang, Daisuke Hashizume, Guang-Yu Guo, Ryotaro Arita, Tetsuo Hanaguri, and Takao Sasagawa
Scanning tunneling microscopy reveals the cause for one kind of electronic symmetry breaking, suggesting avenues for how to exploit it in future, novel devices.
Phys. Rev. X 15, 011033 (2025)
Landau levels, Strain, Valley degrees of freedom, Node-line semimetals, Density functional theory, Scanning tunneling microscopy, Scanning tunneling spectroscopy
Review of Modern Physics
Massive quantum systems as interfaces of quantum mechanics and gravity
Research article | | 2025-02-13 05:00 EST
Sougato Bose, Ivette Fuentes, Andrew A. Geraci, Saba Mehsar Khan, Sofia Qvarfort, Markus Rademacher, Muddassar Rashid, Marko Toroš, Hendrik Ulbricht, and Clara C. Wanjura
The authors review theories and experimental state-of-the-art efforts to study the effects of gravity on massive quantum systems. Classical gravity is the least precisely tested natural force and may be addressed via precision quantum probes. Experiments testing whether the quantum nature of gravity causes decoherence and collapse of matter-wave functions and whether it can mediate entanglement between separate massive particles are underway, and their results will guide the theoretical description of gravity effects on a laboratory scale.
Rev. Mod. Phys. 97, 015003 (2025)
arXiv
Magnetic order through Kondo coupling to quantum spin liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-13 20:00 EST
M. A. Keskiner, M. Ö. Oktel, Natalia B. Perkins, Onur Erten
We study the emergence of magnetic order in localized spins that interact solely through their coupling to a Kitaev-type spin liquid. Using three toy models -- the Kitaev model, the Yao-Lee model, and a square-lattice generalization of the Kitaev model -- we calculate the effective exchange Hamiltonians mediated by the fractionalized excitations of these spin liquids. This setup is analogous to a Kondo lattice model, where conduction electrons are replaced by itinerant Majorana fermions. In the Kitaev model, our results show that the lowest-order perturbation theory generates short-range interactions with modified couplings and extending to sixth order introduces longer-range interactions while preserving the quantum spin-liquid ground state. Models involving more Majorana flavors on honeycomb and square lattices exhibit more complex behavior. The honeycomb Yao-Lee model with three flavors of itinerant Majorana fermions generates long-range RKKY-type interactions, leading to antiferromagnetic order and partial gapping of the Majorana fermion spectrum. In contrast, the square-lattice model produces a combination of anisotropic short- and long-range interactions, which can give rise to either a dimerized quantum paramagnetic state or an Ising antiferromagnet, depending on the parameters. These results illustrate the rich variety of magnetic orders that can be mediated by Kitaev-type spin liquids.
Strongly Correlated Electrons (cond-mat.str-el), Other Condensed Matter (cond-mat.other)
12 pages, 8 figures
Lattice Defects in Rydberg Atom Arrays
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-13 20:00 EST
Hanteng Wang, Chengshu Li, Xingyu Li, Yingfei Gu, Shang Liu
Rydberg atom arrays have become a key platform for studying quantum many-body systems. In these setups, defects arise naturally due to various imperfections and can significantly modify the theoretical predictions compared to an ideal model. Here, we investigate the impact of geometric defects in the simplest situation -- a one-dimensional Rydberg atom array, both at and away from its emergent Ising criticality. In the presence of defects, we demonstrate that relevant physical quantities can be extracted from one-point correlation functions. At the critical point, we show that different types of kinks yield distinct outcomes corresponding to their respective spatial-internal symmetries: site-centered kinks can effectively break the array at the kink position regardless of the kink angle, while bond-centered kinks lead to interesting intermediate-coupling fixed points. In the latter case, due to a special renormalization group flow trajectory, the whole system can appear ordered if the system is not large enough. Additionally, away from criticality, the bond-centered kink induces a localization-delocalization transition of the domain wall, characteristic of quantum wetting. These findings highlight the utility of kinks as experimental probes and stress the importance of controlling defects so that experimental observations remain faithful to the pristine model.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
15 pages, 10 figures
Terahertz electroluminescence from Dirac-Landau polaritons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-13 20:00 EST
B. Benhamou-Bui, C. Consejo, S.S. Krishtopenko, S. Ruffenach, C. Bray, J. Torres, J. Dzian, F. Le Mardelé, A. Pagot, X. Baudry, S.V. Morozov, N.N. Mikhailov, S.A. Dvoretskii, B. Jouault, P. Ballet, M. Orlita, C. Ciuti, F. Teppe
We report intense terahertz electroluminescence from Dirac-Landau polaritons, representing a major step toward achieving stimulated cyclotron emission and polariton-based lasers. By strongly coupling the cyclotron transitions of two-dimensional Dirac fermions in HgTe quantum wells with optical cavity modes, we observe efficient emission near the lasing threshold. This work demonstrates that polariton condensation, a process that bypasses the need for electronic population inversion, can significantly reduce the emission threshold compared to conventional mechanisms requiring high electric fields. Moreover, this concept unlocks the potential for stimulated emission in previously unsuitable narrow-gap semiconductors, as well as Dirac materials with non-equidistant Landau levels. These results open a new way for the development of compact, tunable terahertz lasers based on Landau polaritons, offering new opportunities for solid-state laser technology and applications in the terahertz gap.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics), Quantum Physics (quant-ph)
Manuscript and Supplementary Materials
Imaging van Hove Singularity Heterogeneity in Overdoped Graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-13 20:00 EST
Raymond Blackwell, Zengyi Du, Takuya Okugawa, Asish Kundu, Zebin Wu, Ilya Drozdov, Angel Rubio, Dante Kennes, Kazuhiro Fujita, Abhay Pasupathy
Tuning the chemical potential of a solid to the vicinity of a van Hove singularity (vHS) is a well-established route to discovering emergent quantum phases. In monolayer graphene, the use of electron-donating metal layers has recently emerged as a method to dope the chemical potential to the nearest vHS, as evidenced by Angle-Resolved Photoemission Spectroscopy (ARPES) measurements. In this work, we study the spatial uniformity of the doping from this process using spectroscopic imaging scanning tunneling microscopy (SI-STM). Using molecular beam epitaxy (MBE), we achieve electron doping of graphene on SiC using Ytterbium (Yb-Graphene). We show using in-situ ARPES that the chemical potential is shifted to within 250 meV of the vHS. Using in-situ SI-STM, we establish that there exists significant inhomogeneity in the vHS position in overdoped graphene. We find two separate reasons for this. First, the spatial inhomogeneity of the intercalated Yb leads to local variations in the doping, with a length scale of inhomogeneity set by the screening length of ~ 3 nm. Second, we observe the presence of substitutional Yb dopants in the graphene basal plane. These Yb dopants cause a strong local shift of the doping, along with a renormalization of the quasiparticle amplitude. Theoretical calculations confirm that the Yb impurities effectively change the local potential, thus energetically shifting the position of the van Hove singularity. Our results point to the importance of considering the spatial structure of doping and its inextricable link to electronic structure.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Iterative charge equilibration for fourth-generation high-dimensional neural network potentials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Emir Kocer, Andreas Singraber, Jonas Finkler, Philipp Misof, Tsz Wai Ko, Christoph Dellago, Jörg Behler
Machine learning potentials (MLP) allow to perform large-scale molecular dynamics simulations with about the same accuracy as electronic structure calculations provided that the selected model is able to capture the relevant physics of the system. For systems exhibiting long-range charge transfer, fourth-generation MLPs need to be used, which take global information about the system and electrostatic interactions into account. This can be achieved in a charge equilibration (QEq) step, but the direct solution (dQEq) of the set of linear equations results in an unfavorable cubic scaling with system size making this step computationally demanding for large systems. In this work, we propose an alternative approach that is based on the iterative solution of the charge equilibration problem (iQEq) to determine the atomic partial charges. We have implemented the iQEq method, which scales quadratically with system size, in the parallel molecular dynamics software LAMMPS for the example of a fourth-generation high-dimensional neural network potential (4G-HDNNP) intended to be used in combination with the n2p2 library. The method itself is general and applicable to many different types of fourth-generation MLPs. An assessment of the accuracy and the efficiency is presented for a benchmark system of FeCl\(_3\) in water.
Materials Science (cond-mat.mtrl-sci)
Interpretable and Equation-Free Response Theory for Complex Systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-13 20:00 EST
Response theory provides a pathway for understanding the sensitivity of a system and, more in general, to predict how its statistical properties change as a possibly time-dependent perturbation is applied. Recently discovered general forms of the celebrated Fluctuation-Dissipation Theorem allow for expressing response operators as correlation functions of suitably defined observables in the unperturbed state, also when such a state is far from equilibrium. In the case of complex and multiscale systems, to achieved enhanced practical applicability, response theory must be interpretable, capable of focusing of relevant timescales, and amenable to implemented by data-driven approaches that are potentially equation-agnostic. Complex systems typically exhibit a hierarchy of temporal behaviors, and unresolved or undesired timescales can obscure the dominant mechanisms driving macroscopic responses. As an element of this desired framework, in the spirit of Markov state modelling, we propose here a comprehensive analysis of the linear and nonlinear response of Markov chains to general time-dependent perturbations. We obtain simple and easily implementable formulas that can be used to predict the response of observables as well as higher-order correlations of the system. The methodology proposed here can be implemented in a purely data-driven setting and even if we do not know the underlying evolution equations. The use of algebraic expansions inspired by Koopmanism allow to elucidate the role of different time scales and find explicit and interpretable expressions for the Green's functions at all orders. We illustrate our methodology in a very simple yet instructive metastable system. Finally, our results provide a dynamical foundation for the Prony method, which is commonly used for the statistical analysis of discrete time signals.
Statistical Mechanics (cond-mat.stat-mech), Chaotic Dynamics (nlin.CD), Computational Physics (physics.comp-ph), Data Analysis, Statistics and Probability (physics.data-an)
32 pages, 5 figures
Thermodynamic Uncertainty Relations for Coherent Transport
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-13 20:00 EST
We derive a universal thermodynamic uncertainty relation for Fermionic coherent transport, which bounds the total rate of entropy production in terms of the mean and fluctuations of a single particle current. This bound holds for any multi-terminal geometry and arbitrary chemical and thermal biases, as long as no external magnetic fields are applied. It can further be saturated in two-terminal settings with boxcar-shaped transmission functions and reduces to its classical counterpart in linear response. Upon insertion of a numerical factor, our bound also extends to systems with broken time-reversal symmetry. As an application, we derive trade-off relations between the figures of merit of coherent thermoelectric heat engines and refrigerators, which show that such devices can attain ideal efficiency only at vanishing mean power or diverging power fluctuations. To illustrate our results, we work out a model of a coherent conductor consisting of a chain of quantum dots.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
7+1 pages, 2 figures
Local doping of an oxide semiconductor by voltage-driven splitting of anti-Frenkel defects
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Jiali He, Ursula Ludacka, Kasper A. Hunnestad, Didrik R. Småbråten, Konstantin Shapovalov, Per Erik Vullum, Constantinos Hatzoglou, Donald M. Evans, Erik D. Roede, Zewu Yan, Edith Bourret, Sverre M. Selbach, David Gao, Jaakko Akola, Dennis Meier
Layered oxides exhibit high ionic mobility and chemical flexibility, attracting interest as cathode materials for lithium-ion batteries and the pairing of hydrogen production and carbon capture. Recently, layered oxides emerged as highly tunable semiconductors. For example, by introducing anti-Frenkel defects, the electronic hopping conductance in hexagonal manganites was increased locally by orders of magnitude. Here, we demonstrate local acceptor and donor doping in Er(Mn,Ti)O\(_3\), facilitated by the splitting of such anti-Frenkel defects under applied d.c. voltage. By combining density functional theory calculations, scanning probe microscopy, atom probe tomography, and scanning transmission electron microscopy, we show that the oxygen defects readily move through the layered crystal structure, leading to nano-sized interstitial-rich (p-type) and vacancy-rich (n-type) regions. The resulting pattern is comparable to dipolar npn-junctions and stable on the timescale of days. Our findings reveal the possibility of temporarily functionalizing oxide semiconductors at the nanoscale, giving additional opportunities for the field of oxide electronics and the development of transient electronics in general.
Materials Science (cond-mat.mtrl-sci)
Revealing isotropic abundant low-energy excitations in UTe\(_2\) through complex microwave surface impedance
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-13 20:00 EST
Arthur Carlton-Jones, Alonso Suarez, Yun-Suk Eo, Ian M. Hayes, Shanta R. Saha, Johnpierre Paglione, Nicholas P. Butch, Steven M. Anlage
The complex surface impedance is a well-established tool to study the super- and normal-fluid responses of superconductors. Fundamental properties of the superconductor, such as the pairing mechanism, Fermi surface, and topological properties, also influence the surface impedance. We explore the microwave surface impedance of spin-triplet UTe\(_2\) single crystals as a function of temperature using resonant cavity perturbation measurements employing a novel multi-modal analysis to gain insight into these properties. We determine a composite surface impedance of the crystal for each mode using resonance data combined with the independently measured normal state dc resistivity tensor. The normal state surface impedance reveals the weighting of current flow directions in the crystal of each resonant mode. For UTe\(_2\), we find an isotropic \(\Delta \lambda(T) \sim T^\alpha\) power-law temperature dependence for the magnetic penetration depth for \(T\le T_c/3\) with \(\alpha < 2\), which is inconsistent with a single pair of point nodes on the Fermi surface under weak scattering. We also find a similar power-law temperature dependence for the low-temperature surface resistance \(R_s(T) \sim T^{\alpha_R}\) with \(\alpha_R < 2\). We observe a strong anisotropy of the residual microwave loss across these modes, with some modes showing loss below the universal line-nodal value, to those showing substantially more. We compare to predictions for topological Weyl superconductivity in the context of the observed isotropic power-laws, and anisotropy of the residual loss.
Superconductivity (cond-mat.supr-con)
28 pages, 23 figures
The Augmented Potential Method: Multiscale Modeling Toward a Spectral Defect Genome
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Nutth Tuchinda, Changle Li, Christopher A. Schuh
The modeling of solute chemistry at low-symmetry defects in materials is historically challenging, due to the computation cost required to evaluate thermodynamic properties from first principles. Here, we offer a hybrid multiscale approach called the augmented potential method that connects the chemical flexibility and near-quantum accuracy of a universal machine learning potential at the site of the defect, with the computational speed of a long-range classical potential implemented away from the defect site in a buffer zone. The method allows us to rapidly compute distributions of grain boundary segregation energy for 1,050 binary alloy pairs (including Ag, Al, Au, Cr, Cu, Fe, Mo, Nb, Ni, Pd, Pt, Ta and V, W solvent), creating a database for polycrystalline grain boundary segregation. This database is ~5x larger than previously published spectral compilations, and yet has improved accuracy. The approach can also address problems far beyond the reach of any other method, such as handling bcc Fe-based alloys, or the complex solute-solute interactions in random polycrystals. The approach thus paves a pathway toward a complete defect genome in crystalline materials.
Materials Science (cond-mat.mtrl-sci)
Grain Boundary Segregation Spectra from a Generalized Machine-learning Potential
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Nutth Tuchinda, Christopher A. Schuh
Modeling solute segregation to grain boundaries at near first-principles accuracy is a daunting task, particularly at finite concentrations and temperatures that require accurate assessments of solute-solute interactions and excess vibrational entropy of segregation that are computationally intensive. Here, we apply a generalized machine learning potential for 16 elements, including Ag, Al, Au, Cr, Cu, Mg, Mo, Ni, Pb, Pd, Pt, Ta, Ti, V, W and Zr, to provide a self-consistent spectral database for all of these energetic components in of 240 binary alloy polycrystals. The segregation spectra of Al-based alloys are validated against past quantum-accurate simulations and show improved predictive ability with some existing atom probe tomography experimental data.
Materials Science (cond-mat.mtrl-sci)
Phonon vibrational and transport properties of SnSe/SnS superlattice at finite temperatures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Feng-ning Xue, Wei Li, Zi Li, Yong Lu
The structural stability and phonon properties of SnSe/SnS superlattices at finite temperatures have been studied using machine learning force field molecular dynamics and the anharmonic phonon approach. The vertical SnSe/SnS superlattice undergoes a phase transition from the Pnma phase to a novel P4/nmm phase at finite temperatures, which is different from the high-temperature Cmcm phase of the SnSe and SnS systems. The stability of P4/nmm phase is determined by molecular dynamics trajectories and anharmonic phonon dispersion relations. The imaginary modes of TO modes at the q=M(1/2,1/2,0) point of the P4/nmm phase in harmonic approximation become rigid at elevated temperatures. An analysis of phonon power spectra upon temperature also confirms the dynamic stabilization. The P4/nmm phase has higher symmetry than the Pnma phase, and the phase transition between them is accompanied by competition between the Jahn-Teller effect and phonon anharmonicity. Unlike the anisotropic distribution of Sn-Se/S bonds in the Pnma phase, the P4/nmm phase forms chemical bonds with similar bond lengths both in-plane and interlayer, and their resonance effect can significantly enhance phonon scattering. The calculated phonon density of states and lifetime is strongly temperature dependent, demonstrating the heavy anharmonicity in the SnSe/SnS system. The P4/nmm phase has an extremely low lattice thermal conductivity, close to the experimental values of SnSe and SnS. Moreover, with the reduction of band gap and the enhancement of band degeneracy near the Fermi level, the P4/nmm phase exhibits superior electronic transport properties and significantly enhanced response to infrared and visible light. This makes it show great potential in thermoelectric and photovoltaic applications.
Materials Science (cond-mat.mtrl-sci)
The chemisorption thermodynamics of O\(_2\) and H\(_2\)O on AFM UO\(_2\) surfaces unraveled by DFT+U-D3 study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Yang Huang, Le Zhang, Hefei Ji, Zhipeng Zhang, Qili Zhang, Bo Sun, Haifeng Liu, Haifeng Song
Unraveling the adsorption mechanism and thermodynamics of O\(_2\) and H\(_2\)O on uranium dioxide surfaces is critical for the nuclear fuel storage and uranium corrosion. Based on the first-principles DFT+U-D3 calculations, we carefully test the effect of antiferromagnetic order arrangements on the thermodynamic stability of UO\(_2\) surfaces and propose the 1k AFM surface computational model. The chemisorption states of O\(_2\) and H\(_2\)O on UO\(_2\) (111) surface, suggested by previous experiments, are accurately calculated for the first time. The adsorption properties of O\(_2\) and H\(_2\)O on UO\(_2\)(111) and (110) surfaces are discussed in detail to reveal the different interaction mechanisms. Combined with ab initio atomistic thermodynamics method, we systematically calculate the chemisorption phase diagram and isotherm of O\(_2\) and H\(_2\)O on UO\(_2\) surfaces. Due to the different intermolecular interactions, the monolayer and multilayer adsorption models are identified for O\(_2\) and H\(_2\)O, respectively. This study has comprehensively revealed the different adsorption mechanisms of O\(_2\) and H\(_2\)O on UO\(_2\) surfaces, bridging the electronic structure calculations to the interpretation of experimental results and providing a solid foundation for future theoretical studies of uranium corrosion mechanism in humid air.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
The quantum Mpemba effects
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-13 20:00 EST
Filiberto Ares, Pasquale Calabrese, Sara Murciano
The Mpemba effect, where a hotter system can equilibrate faster than a cooler one, has long been a subject of fascination in classical physics. In the past few years, significant theoretical and experimental progress has been made in understanding its occurrence in both classical and quantum systems. In this review, we provide a concise overview of the Mpemba effect in quantum systems, with a focus on both open and isolated dynamics which give rise to distinct manifestations of this anomalous non-equilibrium phenomenon. We discuss key theoretical frameworks, highlight experimental observations, and explore the fundamental mechanisms that give rise to anomalous relaxation behaviors. Particular attention is given to the role of quantum fluctuations, integrability, and symmetry in shaping equilibration pathways. Finally, we outline open questions and future directions.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
14 pages, 4 figures
Feshbach spectroscopy of ultracold mixtures of \(^{6}{\rm Li}\) and \(^{164}{\rm Dy}\) atoms
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-13 20:00 EST
Ke Xie, Xi Li, Yu-Yang Zhou, Ji-Hong Luo, Shuai Wang, Yu-Zhao Nie, Hong-Chi Shen, Yu-Ao Chen, Xing-Can Yao, Jian-Wei Pan
We report on the observation of Feshbach resonances in ultracold \(^6\mathrm{Li}\)-\(^{164}\mathrm{Dy}\) mixtures, where \(^6\mathrm{Li}\) atoms are respectively prepared in their three lowest spin states, and \(^{164}\mathrm{Dy}\) atoms are prepared in their lowest energy state. We observe 21 interspecies scattering resonances over a magnetic field range from 0 to using atom loss spectroscopy, three of which exhibit relatively broad widths. These broad resonances provide precise control over the interspecies interaction strength, enabling the study of strongly interacting effects in \(^6\mathrm{Li}\)-\(^{164}\mathrm{Dy}\) mixtures. Additionally, we observe a well-isolated interspecies resonance at 700.1 G, offering a unique platform to explore novel impurity physics, where heavy dipolar \(^{164}\mathrm{Dy}\) atoms are immersed in a strongly interacting Fermi superfluid of \(^6\mathrm{Li}\) atoms.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
Homogeneous fermionic Hubbard gases in a flat-top optical lattice
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-13 20:00 EST
Yu-Xuan Wang, Hou-Ji Shao, Yan-Song Zhu, De-Zhi Zhu, Hao-Nan Sun, Si-Yuan Chen, Xing-Can Yao, Yu-Ao Chen, Jian-Wei Pan
Fermionic atoms in a large-scale, homogeneous optical lattice provide an ideal quantum simulator for investigating the fermionic Hubbard model, yet achieving this remains challenging. Here, by developing a hybrid potential that integrates a flat-top optical lattice with an optical box trap, we successfully realize the creation of three-dimensional, homogeneous fermionic Hubbard gases across approximately \(8\times10^5\) lattice sites. This homogeneous system enables us to capture a well-defined energy band occupation that aligns perfectly with the theoretical calculations for a zero-temperature, ideal fermionic Hubbard model. Furthermore, by employing novel radio-frequency spectroscopy, we precisely measure the doublon fraction \(D\) as a function of interaction strength \(U\) and temperature \(T\), respectively. The crossover from metal to Mott insulator is detected, where \(D\) smoothly decreases with increasing \(U\). More importantly, we observe a non-monotonic temperature dependence in \(D\), revealing the Pomeranchuk effect and the development of extended antiferromagnetic correlations.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Epitaxial growth and transport properties of a metallic altermagnet CrSb on a GaAs (001) substrate
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
A newly identified class of magnetic materials called altermagnets has attracted much attention due to the practical properties of spin-splitting bands akin to ferromagnets and small compensated magnetization akin to antiferromagnets. These features make them promising candidates for applications in spintronics devices. Among candidate materials, CrSb is promising due to its high ordering temperature (705 K) and large spin-splitting energy; however, it is predicted that tuning the Néel vector requires additional symmetry breaking or a change in the easy magnetization axis. While applying epitaxial strain can modulate the symmetry, the selection of substrates with closely matched lattice constants for heteroepitaxial growth is limited for altermagnets, which generally have low crystal symmetry. Therefore, exploring the heteroepitaxial growth of altermagnet thin films on well-established, dissimilar crystal systems is valuable. (001)-oriented III-V semiconductors, which share group-V elements with the overgrown CrSb, offer an ideal platform because they are expected to have material compatibility with stable interfaces, as well as tunability of the buffer layer's bandgap and lattice constant by varying the atomic composition of their group-III and group-V atoms. In this study, we have achieved the molecular beam epitaxial growth of a CrSb (\(\bar{1}10\)) thin film on a GaAs (001) substrate by inserting thin FeSb (\(\bar{1}10\)) / AlAs (001) buffer layers. The in-plane epitaxial relationship is found to be CrSb [110] \(\|\) GaAs [110] and CrSb [001] \(\|\) GaAs [\(\bar{1}10\)], and epitaxial strain is also confirmed. We also characterized the magneto-transport properties of the grown CrSb thin film. Although the obtained conductivity tensors are mainly explained by a multi-carrier model, not by an anomalous Hall effect, this model reveals the presence of high-mobility electron and hole carriers.
Materials Science (cond-mat.mtrl-sci)
The manuscript contains 15 pages, 5 figures and 1 table. The supplementary material contains 3 pages and 4 figures
Room-Temperature Deuterium Separation in van der Waals Gap Engineered Vermiculite Quantum Sieves
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Saini Lalita, Rathi Aparna, Kaushik Suvigya, Li-Hsien Yeh, Kalon Gopinadhan
As the demand for nuclear energy grows, enriching deuterium from hydrogen mixtures has become more important. However, traditional methods are either very energy-intensive because they require extremely cold temperatures, or they don't separate deuterium (D2) from regular hydrogen (H2) very well, with a D2/H2 selectivity of about 0.71. To achieve efficient deuterium separation at room temperature, we need materials with very tiny spaces, on an atomic scale. For the first time, we've successfully created a material with spaces just about 2.1 angstroms wide, which is similar in size to the wavelength of hydrogen isotopes at room temperature. This allows for efficient deuterium separation, with a much higher D2/H2 selectivity of about 2.20, meaning the material can separate deuterium from hydrogen much more effectively at room temperature. The smaller deuterium molecules are more likely to pass through these tiny spaces, showing that quantum effects play a key role in this process. In contrast, a material like graphene oxide, with larger spaces (around 4.0 angstroms) only shows a lower D2/H2 selectivity of approx 1.17, indicating weaker quantum effects. This discovery suggests that materials with very small, atomic-scale spaces could be key to the efficient separation of hydrogen isotopes at room temperature.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
24 pages including supporting information, 4 main figures, 10 Supporting figures
Long-Lived Coherence between Incoherent Excitons revealed by Time-Resolved ARPES: An Exact Solution
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Zhenlin Zhang, Wei Hu, Enrico Perfetto, Gianluca Stefanucci
We investigate the exciton dynamics in an exactly solvable two-band model for semiconductors. The model incorporates light-matter, electron-electron and electron-phonon interactions, and captures exciton formation as well as the transition from the coherent to the incoherent regime. We analyze excitonic polarization, populations and coherences, with special focus on their impact in Time-Resolved and Angle-Resolved Photoemission Spectroscopy (TR-ARPES). For nonresonant pumping with below-gap photon energies, TR-ARPES spectra reveal distinct excitonic replica and quantum beats persisting in the incoherent regime. These are due to a coherence between different species of {} excitons. Such type of coherence is resistant to phonon dephasing, indicating that it follows different dynamics than those governing the coherences considered so far.
Materials Science (cond-mat.mtrl-sci)
15 pages, 5 figures
Influence of 14N hyperfine interaction on electron nuclear double resonance of boron vacancy in hexagonal boron nitride
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
G.V. Mamin, E.V. Dmitrieva, F.F. Murzakhanov, I.N. Gracheva, V.A. Soltamov, M.R. Gafurov
The research focuses on the explanation of a phenomenon observed in the spectra of electron nuclear resonance (ENDOR) pertaining to nitrogen atoms adjacent to the boron vacancy (VB) defect in hexagonal boron nitride (hBN). The phenomenon is manifested as a shift of the ENDOR spectrum lines with respect to the nitrogen Larmor frequency. It is hypothesized that these shifts are indicative of a substantial hyperfine interaction between the VB defect and the 14N nuclei in hBN. A calculation utilizing second-order perturbation theory was executed to determine the positions of the ENDOR spectrum lines, resulting in the formulation of correction equations. The values obtained from the perturbation theory corrections align well with the experimental results. The extent of nuclear state admixture into electron states was found to be around 0.04-0.07%.
Materials Science (cond-mat.mtrl-sci)
Magnetic Resonance in Solids, 2025, Vol.27, No.1, 25102 (9 pp)
Strong and Tunable Electrical-Anisotropy in Type-II Weyl Semimetal Candidate WP2 with Broken Inversion Symmetry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Bo Su, Yanpeng Song, Yanhui Hou, Xu Chen, Jianzhou Zhao, Yongchang Ma, Yang Yang, Jiangang Guo, Jianlin Luo, Zhi-Guo Chen
A transition metal diphosphide WP2 is a candidate for type-II Weyl semimetals (WSMs) in which spatial inversion symmetry is broken and Lorentz invariance is violated. As one of the key prerequisites for the presence of the WSM state in WP2, spatial inversion symmetry breaking in this compound has rarely been investigated by experiments. Furthermore, how much anisotropy the electrical properties of WP2 have and whether its electrical anisotropy can be tuned remain elusive. Here, we report angle-resolved polarized Raman spectroscopy, electrical transport, optical spectroscopy and first-principle studies of WP2. The energies of the observed Raman-active phonons and the angle dependences of the phonon intensities are well consistent with the results obtained by first-principle calculations and the analysis of the proposed crystal symmetry without spatial inversion, providing evidence that spatial inversion symmetry is broken in WP2. Moreover, the measured ratio (Rc/Ra) between the crystalline c-axis and a-axis electrical resistivities exhibits a weak dependence on temperature from 100 to 250 K, but increases abruptly below 100 K, and then reaches the value of 8.0 at 10 K, which is by far the strongest in-plane electrical resistivity anisotropy among the reported type-II WSM candidates with comparable carrier concentrations. Our optical-spectroscopy and calculation studies reveal that the abrupt enhancement of the Rc/Ra below 100 K mainly arises from a sharp increase in the scattering rate anisotropy at low temperatures. More interestingly, the Rc/Ra at 10 K can be tuned from 8.0 to 10.6 as the magnetic field increases from 0 to 9 T. The stronge and tunable electrical resistivity anisotropy found in WP2 can serve as a degree of freedom for tuning the electrical properties of type-II WSMs, which paves the way for developing novel electronic applications based on type-II WSMs.
Materials Science (cond-mat.mtrl-sci)
Published in Advanced Materials
Advanced Materials 31, 1903498 (2019)
Chiral Topological Phononic Quasiparticles in Enantiomeric Crystals SrSi\(_2\) and BaSi\(_2\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Yong-Kun Wang, An-Dong Fan, Jin-Yang Li, Huaqing Huang, Si Li
Chiral crystals have recently garnered significant interest in condensed matter physics due to their unique electronic and optical properties. In this paper, we explore the connection between the chirality of crystal structures and the chirality of topological quasiparticles. We specifically predict and analyze several chiral enantiomeric materials, such as SrSi\(_2\) and BaSi\(_2\), which crystallize in the chiral space groups \(P4{_3}32\) and \(P4{_1}32\). Based on first-principles calculations and theoretical analysis, we reveal that the phonon spectra of these materials host various topological phononic quasiparticles, including charge-2 triple points, charge-2 Dirac points, charge-2 Weyl points, and charge-1 Weyl points. Our paper shows that in these enantiomeric materials, the opposite chirality of the crystal structure results in topological quasiparticles with opposite chiral topological charges and distinct topological surface states. Our paper elucidates the intrinsic relationship between the chirality of crystal structures and the chirality of topological quasiparticles, providing promising theoretical guidance and material platform for investigating the physical properties of chiral crystals.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 4 figures
Phys. Rev. B 111, 075119 (2025)
Breakdown of Magic Numbers in Spherical Confinement
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-13 20:00 EST
Junwei Wang, Jonathan Martín-González, Lukas Römling, Silvan Englisch, Chrameh Fru Mbah, Praveen Bommineni, Erdmann Spiecker, Michael Engel, Nicolas Vogel
Magic numbers in finite particle systems correspond to specific system sizes that allow configurations with low free energy, often exhibiting closed surface shells to maximize the number of nearest neighbors. Since their discovery in atomic nuclei, magic numbers have been essential for understanding the number-structure-property relationship in finite clusters across different scales. However, as system size increases, the significance of magic numbers diminishes, and the precise system size at which magic number phenomena disappear remains uncertain. In this study, we investigate colloidal clusters formed through confined self-assembly. Small magic number clusters display icosahedral symmetry with closed surface shells, corresponding to pronounced free energy minima. Our findings reveal that beyond a critical system size, closed surface shells disappear, and free energy minima become less pronounced. Instead, we observe a distinct type of colloidal cluster, termed football cluster, which retains icosahedral symmetry but features lower-coordinated facets disconnected by terraces. A sphere packing model demonstrates that forming closed surface shells becomes impossible beyond a critical system size, explaining the breakdown of magic numbers in large confined systems.
Soft Condensed Matter (cond-mat.soft), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
16 pages, 5 figures (main text) and 15 pages, 15 figures (supplementary materials)
Probing the many-body localized spin-glass phase through quench dynamics
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-13 20:00 EST
Pietro Brighi, Marko Ljubotina, Maksym Serbyn
Eigenstates of quantum many-body systems are often used to define phases of matter in and out of equilibrium; however, experimentally accessing highly excited eigenstates is a challenging task, calling for alternative strategies to dynamically probe nonequilibrium phases. In this work, we characterize the dynamical properties of a disordered spin chain, focusing on the spin-glass regime. Using tensor-network simulations, we observe oscillatory behavior of local expectation values and bipartite entanglement entropy. We explain these oscillations deep in the many-body localized spin glass regime via a simple theoretical model. From perturbation theory, we predict the timescales up to which our analytical description is valid and confirm it with numerical simulations. Finally, we study the correlation length dynamics, which, after a long-time plateau, resumes growing in line with renormalization group (RG) expectations. Our work suggests that RG predictions can be quantitatively tested against numerical simulations and experiments, potentially enabling microscopic descriptions of dynamical phases in large systems.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Superconducting Diode Effect in Selectively-Grown Topological Insulator based Josephson Junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-13 20:00 EST
Gerrit Behner, Abdur Rehman Jalil, Detlev Grützmacher, Thomas Schäpers
The Josephson diode effect, where the critical current magnitude depends on its direction, arises when both time-reversal and inversion symmetries are broken - often achieved by a combination of spin-orbit interaction and applied magnetic fields. Taking advantage of the strong spin-orbit coupling inherent in three-dimensional topological insulators, we study this phenomenon in Nb/Bi\(_{0.8}\)Sb\(_{1.2}\)Te\(_3\)/Nb Josephson weak-link junctions. Under an in-plane magnetic field perpendicular to the current direction, we observe a pronounced Josephson diode effect with efficiencies up to 7%. A crucial component of this behavior is the non-sinusoidal current-phase relationship and an anomalous phase shift, which we attribute to the presence of a ballistic supercurrent component due to the surface states. These findings open up new avenues for harnessing and controlling the Josephson diode effect in topological material systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 4 figures, 8 pages supplemental material including 8 figures
Demonstration of the third-order nonlinear Hall effect in topological Dirac semimetal NiTe\(_2\)
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-13 20:00 EST
V.D. Esin, A.V. Timonina, N.N. Kolesnikov, E.V. Deviatov
We experimentally investigate third-order nonlinear Hall effect for three-dimensional NiTe\(_2\) single crystal samples. NiTe\(_2\) is the recently discovered type-II Dirac semimetal, so both the inversion and the time-reversal symmetries are conserved in the bulk. As a result, the well known second-order nonlinear Hall effect does not expected for this material, which we confirm as negligibly small second-harmonic transverse Hall voltage response to the longitudinal ac electric current. As the main experimental result, we demonstrate the unsaturated third-harmonic Hall response in NiTe\(_2\), which well corresponds to the theoretically predicted third-order nonlinear Hall effect in Dirac semimetals. We also demonstrate, that the third harmonic signal does not depend on the external magnetic field, in contrast to the field-depended first-order and second-order Hall effects.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
5 pages, 3 Postscript figures
Identification of orbital pumping from spin pumping and rectification effects
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Nils Keller, Arnab Bose, Nozomi Soya, Elias Hauth, Fabian Kammerbauer, Rahul Gupta, Hiroki Hayashi, Hisanobu Kashiki, Gerhard Jakob, Sachin Krishnia, Kazuya Ando, Mathias Kläui
The recently predicted mechanism of orbital pumping enables the generation of pure orbital current from a precessing ferromagnet (FM) without the need for electrical current injection. This orbital current can be efficiently injected into an adjacent nonmagnetic material (NM) without being hampered by electrical conductivity mismatch. However, experimentally identifying this novel effect presents significant challenges due to the substantial background contributions from spin pumping and spin rectification effects (SREs). In this work, we disentangle the effects of orbital pumping from spin pumping in bilayer structures composed of Nb/Ni and Nb/\(\mathrm{Fe_{60}Co_{20}B_{20}}\) by observing a sign reversal of the measured voltage. This reversal arises from the competing signs of the spin and orbital Hall effects in the Nb. We establish methods to differentiate the pumping signal from SREs by analyzing the distinct angular dependence of the measured voltage and its spatial dependence relative to the radio frequency excitation source.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Superconductivity near an Ising nematic quantum critical point in two dimensions
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-13 20:00 EST
Jie Huang, Zhao-Kun Yang, Jing-Rong Wang, Guo-Zhu Liu
Near a two-dimensional Ising-type nematic quantum critical point, the quantum fluctuations of the nematic order parameter are coupled to the electrons, leading to non-Fermi liquid behavior and unconventional superconductivity. The interplay between these two effects has been extensively studied through the Eliashberg equations for the superconducting gap. However, previous studies often rely on various approximations that may introduce uncertainties in the results. Here, we revisit this problem without these approximations and examine how their removal changes the outcomes. We numerically solve four self-consistent Eliashberg integral equations of the mass renormalization \(A_{1}(p)\), the chemical potential renormalization \(A_{2}(p)\), the pairing function \(\Phi(p)\), and the nematic self-energy (polarization) function \(\Pi(q)\) using the iteration method. Our calculations retain the explicit non-linearity and the full momentum dependence of these equations. We find that discarding some commonly used approximations allows for a more accurate determination of the superconducting gap \(\Delta = \Phi/A_{1}\) and the critical temperature \(T_{c}\). The Eliashberg equations have two different convergent gap solutions: an extended \(s\)-wave gap and a \(d_{x^{2}-y^{2}}\)-wave gap. The latter is fragile, whereas the former is robust against small perturbations.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 5 figures
Beyond the orbitally-resolved magnetic exchange in CrI\(_{3}\) and NiI\(_{2}\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Denis Šabani (1), Cihan Bacaksız (1), Milorad V. Milošević (1) ((1) University of Antwerp, Antwerp, Belgium)
The pertinent need for microscopic understanding of magnetic exchange motivated us to go beyond the existing theories and develop a systematic method to quantify all possible mechanisms that contribute to magnetic exchange for an arbitrary pair of atoms in a given material. We apply it to the archetypal 2D magnetic monolayers CrI3 and NiI2, to reveal the previously underrated dx2-y2,dx2-y2 contribution as either the leading or the second largest contribution to the total magnetic exchange. We proceed to explore the microscopic mechanisms behind all the non-zero orbital contributions in both CrI3 and NiI2, and generalize the findings to other magnetic monolayers dominated by d8 and d3 electronic configurations of the magnetic atoms.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Chiral breakdown engineered by mesoscale Dzyaloshinskii-Moriya interaction in biaxial magnetic nanotubes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-13 20:00 EST
Kostiantyn V. Yershov, Svitlana Kondovych, Denis D. Sheka
Curvilinear geometries in magnetic nanostructures provide a unique platform for exploring the interplay of symmetry, topology, and curvature in magnetization dynamics. In this work, we analytically study the static and dynamic properties of domain walls in biaxial magnetic nanotubes with intrinsic Dzyaloshinskii-Moriya interaction of different symmetries. We show that geometry-driven local and nonlocal interactions govern domain profiles and dynamics, enabling precise control over the wall propagation and Walker breakdown field. Furthermore, the combination of bulk-type Dzyaloshinskii-Moriya interaction and curvature leads to chirality symmetry breaking and chiral breakdown in domain wall motion. These findings offer a framework for tailoring domain wall textures in cylindrical nanotubes, unlocking new functionalities for advanced applications in curvilinear magnonics and data storage technologies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Angular dependent ferromagnetic resonance of exfoliated yttrium iron garnet film under stress
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Yufeng Wang, Peng Zhou, Shuai Liu, Yajun Qi, Tianjin Zhang
Yttrium iron garnet (Y3Fe5O12, YIG) plays a significant role in the field of spintronics due to its low magnetic damping and insulating characteristics. However, most studies have focused on YIG in bulk form or as film grown on rigid substrates. In this study, YIG film has been exfoliated from two-layer-graphene covered (111) Gd3Ga5O12 (GGG) substrate. Magnetic properties of YIG film under stress are investigated in detail via angular dependent ferromagnetic resonance. The relationship between magnetic parameters and compressive/tensile stress has been established. The findings of this work will be beneficial for the applications of flexible YIG film.
Materials Science (cond-mat.mtrl-sci)
Dendrite suppression in fast-charging high-energy metal-ion batteries: a Bayesian optimization approach
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Hamed Taghavian, Viktor Vanoppen, Erik Berg, Peter Broqvist, Jens Sjölund
Metal anodes provide the highest possible energy density in batteries. However, challenges associated with electrode/electrolyte interface side reactions and dendrite growth remain unsolved, especially under fast-charging conditions. In this paper, we consider a phase-field model of electrodeposition and optimize its parameters for suppressing dendrite growth and accelerating charging speed under constant voltage. We identify interfacial mobility as a key parameter, which should be maximized to inhibit dendrites without compromising the charging speed. The proposed approach provides a versatile tool for designing battery cells by optimizing an arbitrary objective function using an arbitrary set of parameters. This approach is based on Bayesian optimization and explores the parameters space with a high sample efficiency and a low computation complexity. The results are verified using extended simulations of dendrite evolution in charging half cells with lithium-metal anodes.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Emergent dimer-model topological order and quasi-particle excitations in liquid crystals: combinatorial vortex lattices
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-13 20:00 EST
Cuiling Meng, Jin-Sheng Wu, Žiga Kos, Jörn Dunkel, Cristiano Nisoli, Ivan I. Smalyukh
Liquid crystals have proven to provide a versatile experimental and theoretical platform for studying topological objects such as vortices, skyrmions, and hopfions. In parallel, in hard condensed matter physics, the concept of topological phases and topological order has been introduced in the context of spin liquids to investigate emergent phenomena like quantum Hall effects and high-temperature superconductivity. Here, we bridge these two seemingly disparate perspectives on topology in physics. Combining experiments and simulations, we show how topological defects in liquid crystals can be used as versatile building blocks to create complex, highly degenerate topological phases, which we refer to as 'Combinatorial Vortex Lattices' (CVLs). CVLs exhibit extensive residual entropy and support locally stable quasi-particle excitations in the form of charge-conserving topological monopoles, which can act as mobile information carriers and be linked via Dirac strings. CLVs can be rewritten and reconfigured on demand, endowed with various symmetries, and modified through laser-induced topological surgery - an essential capability for information storage and retrieval. We demonstrate experimentally the realization, stability, and precise optical manipulation of CVLs, thus opening new avenues for understanding and technologically exploiting higher-hierarchy topology in liquid crystals and other ordered media.
Soft Condensed Matter (cond-mat.soft)
Optimization of magnetic contrast layer for neutron reflectometry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Anton Zubayer, Fredrik Eriksson, Naureen Ghafoor, Jochen Stahn, Jens Birch, Artur Glavic
Neutron reflectivity is a powerful technique for probing density profiles in films, with applications across Physics, Chemistry, and Biology. However, challenges arise when dealing with samples characterized by high roughness, unknown scattering length density (SLD) with low contrast, very thin layers, or complex multi-layered structures, that cannot be uniquely resolved due to the phase problem. Incorporating a magnetic reference layer (MRL) and using polarized neutron reflectivity improves sensitivity and modeling accuracy by providing complementary information. In this study, we introduce a quantitative way to compare MRL systems in a model-free way. We apply this approach to demonstrate that CoTi alloys offer a superior solution as an MRL compared to the commonly used Fe or Ni-based MRLs. The low nuclear and magnetic scattering length densities of CoTi significantly enhance sensitivity, making it particularly advantageous for soft matter research. Furthermore, the tunable Co vs Ti ratio allows for optimization of the SLDs to achieve maximum sensitivity, establishing CoTi as a highly effective choice for MRL applications. The applied simulation framework for optimizing MRL sensitivity to a specific materials system and research question is a generic approach that can be used prior to growing the MRL for a given experiment.
Materials Science (cond-mat.mtrl-sci)
Magnetic hysteresis control in thin film Fe/Si multilayers by incorporation of B4C
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Anton Zubayer, Takayasu Hanashima, Jun Sugiyama, Anna David, Xianjie Liu, Naureen Ghafoor, Jochen Stahn, Artur Glavic, Yasukazu Murakami, Tamaoka Takehiro, Yuta Tomita, M. Auchi, Jens Birch, Mats Fahlman, Fredrik Eriksson
Magnetic hysteresis properties in Fe/Si multilayers have been studied as a function of the B4C content to control magnetization amplitude, coercivity, and hysteresis tilt, properties that are beneficial to tune for advancing applications in e.g. data storage, spintronics, and sensors. With an ion-assisted magnetron sputtering technique, 35 distinct thin film multilayer samples were prepared and their magnetic and structural properties were characterized by vibrating sample magnetometry, X-ray photoelectron spectroscopy, near edge X-ray absorption fine structure spectroscopy, and X-ray and neutron scattering methods. Key findings indicate that adding B4C lowers the coercivity and can decrease the saturation magnetization, demonstrating the tunability of magnetic responses based on composition. For samples with =30Å periodicity, 10-15% of B4C addition produces antiferromagnetically (AF) coupled multilayers, and such AF coupling strength increases with the B4C content. Our findings reveal that B atoms do not chemically bind within the Fe atoms but instead occupy interstitial positions, disrupting medium- to long-range crystallinity thereby inducing the amorphization. Thereon, the observed effects on magnetic properties are directly attributed to this amorphization process caused by the presence of B4C. The demonstrated ability to finely adjust magnetic properties by varying the B4C content offers a promising approach to overcome challenges in magnetic device performance and efficiency.
Materials Science (cond-mat.mtrl-sci)
Skyrmion motion in a synthetic antiferromagnet driven by asymmetric spin wave emission
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-13 20:00 EST
Christopher E. A. Barker, Charles Parton-Barr, Christopher H. Marrows, Olga Kazakova, Craig Barton
Skyrmions have been proposed as new information carriers in racetrack memory devices. To realise such devices, a small size; high speed of propagation; and minimal skyrmion Hall angle are required. Synthetic antiferromagnets (SAFs) present the ideal materials system to realise these aims. In this work, we use micromagnetic simulations to propose a new method for manipulating them using exclusively global magnetic fields. An out-of-plane microwave field induces oscillations in the skyrmions radius which in turn emits spin waves. When a static in-plane field is added, this breaks the symmetry of the skyrmions and causes asymmetric spin wave emission. This in turn drives motion of the skyrmions, with the fastest velocities observed at the frequency of the intrinsic out-of-phase breathing mode of the pair of skyrmions. This behaviour is investigated over a range of experimentally realistic antiferromagnetic interlayer exchange coupling strengths, and the results compared to previous works studying similar motion driven with an oscillating electric field. Through this the true effect of varying the exchange coupling strength is determined, and greater insight is gained into the mechanism of skyrmion motion. These results will help to inform the design of future novel computing architectures based on the dynamics of skyrmions in synthetic antiferromagnets.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Thermal behavior of Bose-Einstein condensates of polar molecules
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-13 20:00 EST
Juan Sánchez-Baena, Gerard Pascual, Raúl Bombín, Ferran Mazzanti, Jordi Boronat
We use the finite-temperature extended Gross-Pitaevskii equation (TeGPE) to study a condensate of dipolar NaCs molecules under the conditions of the very recent, breakthrough experiment [Bigagli this http URL., Nature 631, 289 (2024)]. We report the condensate fraction of the system, and its density profile after a time-of flight expansion for the coldest experimental case, finding excellent agreement with the experimental measurements. We also report the peak density of the ground state and establish a comparison with the experimental estimates. Our results, derived from the TeGPE formalism, successfully describe the Bose-Einstein condensation of polar molecules at finite temperature.
Quantum Gases (cond-mat.quant-gas)
4 pages, 4 figures
Metamagnetic quantum criticality in the antiferromagnetic topological insulator MnBi\(_2\)Te\(_4\)
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Tithiparna Das, Soumik Mukhopadhyay
Combining transport and magnetization measurements, we discover the emergence of a tricritical point connecting the antiferromagnetic, metamagnetic and paramagnetic regions in MnBi\(_2\)Te\(_4\), a magnetic topological insulator candidate which can potentially exhibit axion electrodynamics. We observe a unique magnetic field-driven phase diagram where the second-order antiferromagnetic to paramagnetic phase boundary bifurcates into two first-order lines at the tricritical point. The two first-order lines enclosing the metamagnetic phase eventually terminate at the quantum critical endpoints with the application of magnetic field.
Materials Science (cond-mat.mtrl-sci)
Tuning the chiral orbital currents in a colossal magnetoresistive nodal line ferrimagnet
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Arnab Das, Soumik Mukhopadhyay
The ferrimagnetic nodal-line semiconductor Mn\(_3\)Si\(_2\)Te\(_6\) exhibits colossal magnetoresistance (CMR) owing to the chiral orbital currents (COC). The COC is developed due to spin-orbit interaction (SOI) attributed to the tellurium (Te) atoms. Here, we observe that on chemical substitution of the Te atoms with selenium (Se), the COC, which runs along the Te-Te edges of the MnTe\(_6\) octahedra, becomes weaker and thus affects the angular magnetoresistance (MR) of Mn\(_3\)Si\(_2\)Te\(_6\). We find that the application of magnetic field along the easy axis leads to a considerable drop in resistance in substituted crystals, which otherwise exhibits weak MR. On the other hand, the CMR effect along the partially polarized magnetization direction is found to be only marginally affected due to the substitution and persists even for a significantly high concentration of Se.
Materials Science (cond-mat.mtrl-sci)
Kitaev-Ising-\(J_1\)-\(J_2\) model: a density matrix renormalization group study
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-13 20:00 EST
A. V. Kapranov, R. S. Akzyanov
We numerically study the Kitaev honeycomb model with the additional XX Ising interaction between the nearest and the next nearest neighbors (Kitaev-Ising-\(J_1\)-\(J_2\) model), by using the density matrix renormalization group (DMRG) method. Such additional interaction correspond to the nearest and diagonal interactions on the square lattice. Phase diagram of the bare Kitaev model consist of low entangled commensurate magnetic phases and entagled Kitaev spin liquid. Anisotropic Ising interaction allows the entangled incommensurate magnetic phases in the phase diagram, which previously was predicted only for more complex type of interactions. We study the scaling law of the entanglement entropy and the bond dimension of the matrix product state with the size of the system. In addition, we propose an optimization algorithm to prevent DMRG from getting stuck in the low-entangled phases.
Strongly Correlated Electrons (cond-mat.str-el)
Multicomponent one-dimensional quantum droplets across the mean-field stability regime
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-13 20:00 EST
I. A. Englezos, P. Schmelcher, S. I. Mistakidis
The Lee-Huang-Yang (LHY) energy correction at the edge of the mean-field stability regime is known to give rise to beyond mean-field structures in a wide variety of systems. In this work, we analytically derive the LHY energy for two-, three- and four-component one-dimensional bosonic short-range interacting mixtures across the mean-field stability regime. For varying intercomponent attraction in the two-component setting, quantitative deviations from the original LHY treatment emerge being imprinted in the droplet saturation density and width. On the other hand, for repulsive interactions an unseen early onset of phase-separation occurs for both homonuclear and heteronuclear mixtures. Closed LHY expressions for the fully-symmetric three- and four-component mixtures, as well as for mixtures comprised of two identical components coupled to a third independent component are provided and found to host a plethora of mixed droplet states. Our results are expected to inspire future investigations in multicomponent systems for unveiling exotic self-bound states of matter and unravel their nonequilibrium quantum dynamics.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph)
18 pages, 6 figures
Full-cycle device-scale simulations of memory materials with a tailored atomic-cluster-expansion potential
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Yuxing Zhou, Daniel F. Thomas du Toit, Stephen R. Elliott, Wei Zhang, Volker L. Deringer
Computer simulations have long been key to understanding and designing phase-change materials (PCMs) for memory technologies. Machine learning is now increasingly being used to accelerate the modelling of PCMs, and yet it remains challenging to simultaneously reach the length and time scales required to simulate the operation of real-world PCM devices. Here, we show how ultra-fast machine-learned interatomic potentials, based on the atomic cluster expansion (ACE) framework, enable simulations of PCMs reflecting applications in devices with excellent scalability on high-performance computing platforms. We report full-cycle simulations -- including the time-consuming crystallisation process (from digital "zeroes" to "ones") -- thus representing the entire programming cycle for cross-point memory devices. We also showcase a simulation of full-cycle operations, relevant to neuromorphic computing, in a mushroom-type device geometry. Our work provides a springboard for the atomistic modelling of PCM-based memory and neuromorphic computing devices -- and, more widely, it illustrates the power of highly efficient ACE ML models for materials science and engineering.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Ferromagnetic Resonance in a Magnetically Dilute Percolating Ferromagnet: An Experimental and Theoretical Study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Y.K. Edathumkandy, K. Das, K. Gas, D. Sztenkiel, D. Hommel, H. Przybylińska, M. Sawicki
Ferromagnetic resonance (FMR) serves as a powerful probe of magnetization dynamics and anisotropy in percolating ferromagnets, where short-range interactions govern long-range magnetic order. We apply this approach to Ga\(_{1-x}\)Mn\(_x\)N (\(x \simeq 8\)), a dilute ferromagnetic semiconductor, combining FMR and superconducting quantum interference device magnetometry. Our results confirm the percolative nature of ferromagnetism in (Ga,Mn)N, with a Curie temperature \(T_{\mathrm{C}} = 12\) K, and reveal that despite magnetic dilution, key features of conventional ferromagnets are retained. FMR measurements establish a robust uniaxial anisotropy, dictated by Mn\(^{3+}\) single-ion anisotropy, with an easy-plane character at low Mn content. While excessive line broadening suppresses FMR signals below 9 K, they persist up to 70 K, indicating the presence of non-percolating ferromagnetic clusters well above \(T_{\mathrm{C}}\). The temperature dependence of the FMR intensity follows that of the magnetization, underscoring the stability of these clusters. Analysis of the FMR linewidth provides insights into relaxation processes, revealing large Gilbert damping due to the low magnetization of the system. Strikingly, atomistic spin model simulations reproduce the experimentally observed resonance fields, anisotropy trends, and linewidth evolution with remarkable accuracy. This agreement underscores the predictive power of our modeling approach in describing percolating ferromagnets. This study advances the understanding of percolating ferromagnetic systems, demonstrating that FMR is a key technique for probing their unique dynamic and anisotropic properties. Our findings contribute to the broader exploration of dilute ferromagnets and provide new insights into percolating ferromagnetic systems, which will be relevant for spintronic opportunities.
Materials Science (cond-mat.mtrl-sci)
16 pages, 17 figures
Acceleration of crystal structure relaxation with Deep Reinforcement Learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Elena Trukhan, Efim Mazhnik, Artem R. Oganov
We introduce a Deep Reinforcement Learning (DRL) model for the structure relaxation of crystal materials and compare different types of neural network architectures and reinforcement learning algorithms for this purpose. Experiments are conducted on Al-Fe structures, with potential energy surfaces generated using EAM potentials. We examine the influence of parameter settings on model performance and benchmark the best-performing models against classical optimization algorithms. Additionally, the model's capacity to generalize learned interaction patterns from smaller atomic systems to more complex systems is assessed. The results demonstrate the potential of DRL models to enhance the efficiency of structure relaxation compared to classical optimizers.
Materials Science (cond-mat.mtrl-sci)
Structural and optical properties of in situ Eu-doped ZnCdO/ZnMgO superlattices grown by plasma-assisted molecular beam epitaxy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Anastasiia Lysak, Aleksandra Wierzbicka, Sergio Magalhaes, Piotr Dlzewski, Rafal Jakiela, Michal Szot, Zeinab Khosravizadeh, Abinash Adhikari, Adrian Kozanecki, Ewa Przezdziecka
In situ Eu-doped ZnCdO-ZnMgO superlattices with varying ZnCdO:Eu and ZnMgO sublayers thicknesses were deposited by plasma assisted molecular beam epitaxy.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 Figures
Amoeboid propulsion of active solid bodies, vesicles and droplets: a comparison
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-13 20:00 EST
Reiner Kree, Annette Zippelius
We present a unified discussion of three types of near-spherical amoeboid microswimmers, driven by periodic, axially symmetric, achiral deformations (swim strokes): a solid deformable body, a vesicle with incompressible fluid membrane, and a droplet. Minimal models are used, which characterize the swimmer type only by boundary conditions. We calculate the swimming velocities, the dissipated power and the Lighthill efficiencies within a second order perturbation expansion in the small deformation amplitudes. %Our approach uses spherical harmonics to represent surface deformations and a system of general solutions of the Stokes equation based on vector spherical harmonics. For solid bodies, we reproduce older results by Lighthill and Blake, for vesicles and for droplets we add new results. The unified approach allows for a detailed comparison between the three types of microswimmers. We present such comparisons for swim strokes made up of spherical harmonics of adjacent orders \(l\) and \(l+1\), as well as for a manifold of swim strokes, made up of spherical harmonics up to order \(l=4\), which respect volume- and surface-incompressibility. This manifold is two-dimensional, which allows to present swimming velocities and efficiencies in a compact graphical form. In a race in which each swimmer can choose the stroke that maximizes its speed, the droplet always comes in first, the vesicle comes in second, while the particle finishes third. However, if the three swimmers perform the same stroke, other order of rankings become possible. The maximum of the total efficiency of a droplet is greater than that of a vesicle if the internal dissipation is small. The efficiency of the solid body turns out to be typically two orders of magnitude smaller than that of vesicles and droplets. Optimizing the Lighthill efficiency and optimizing the swimming velocity result in different optimal swim strokes
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Interlayer interactions in \(\text{La}_3\text{Ni}_2\text{O}_7\) under pressure: from \(s^{\pm}\) to \(d_{xy}\)-wave superconductivity
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-13 20:00 EST
Lauro B. Braz, George B. Martins, Luis G. G. V. Dias da Silva
We investigate the role of interaction terms in the competition between different superconducting gap symmetries in the bilayer nickelate \(\text{La}_3\text{Ni}_2\text{O}_7\) under high pressure. We study a two-layer, two-orbital electron model that encompasses both intra- and interlayer Coulomb interaction terms within the matrix random-phase approximation. We find that interlayer interactions favor a \(d_{xy}\)-wave superconducting pairing symmetry over the \(s^{\pm}\)-wave symmetry, which has been found to prevail when interlayer interactions are disregarded. Moreover, our findings indicate that interlayer interactions enhance the interorbital pairing, incorporating contributions from all three electron pockets, arising from both \(d_{3z^2-r^2}\) and \(d_{x^2-y^2}\) orbital character, resulting in nodes within the gap function (not present in the \(s^{\pm}\)-wave state) and consequently favoring the \(d_{xy}\)-wave pairing.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
5 pages, 4 figures + Supp. Material
Microscopic mechanism of electric field-induced superconductivity suppression in metallic thin films
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-13 20:00 EST
Alessio Zaccone, Giovanni A. Ummarino, Alessandro Braggio, Francesco Giazotto
Supercurrent field-effect transistors made from thin metallic films are a promising option for next-generation high-performance computation platforms. Despite extensive research, there is still no complete quantitative microscopic explanation for how an external DC electric field suppresses superconductivity in thin films. This study aims to provide a quantitative description of superconductivity as a function of film thickness based on Eliashberg's theory. The calculation considers the electrostatics of the electric field, its realistic penetration depth in the film, and its effect on the Cooper pair, which is described as a standard s-wave bound state according to BCS theory. The estimation suggests that an external electric field of approximately \(10^8\) V/m is required to suppress superconductivity in 10-30-nm-thick films, which aligns with experimental observations. Ultimately, the study offers "materials by design" guidelines for suppressing supercurrent when an external electric field is applied to the film surface. Furthermore, the proposed framework can be easily extended to investigate the same effects for ultrathin films.
Superconductivity (cond-mat.supr-con), Disordered Systems and Neural Networks (cond-mat.dis-nn), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Screening and localization in the nonlinear Anderson problem
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-13 20:00 EST
Alexander V. Milovanov, Alexander Iomin
We resolve an existing question concerning the localization of a wave packet by random potential in the presence of weak nonlinearity. The problem has gained considerable interest in the literature, and it continues to attract attention due to its connection with the general properties of behavior of systems with competition between nonlinearity, nonlocality and randomness. We find that the nonlinearly localized state occurs through a finite polarization response from the lattice well beyond the assumptions of a perturbation-theory approach. For the vanishing polarization response the nonlinear localization length diverges permitting unlimited spreading of the nonlinear field.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
6 pages, 1 figure
Thiolation and PEGylation of silicon carbide nanoparticle
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Péter Rózsa, Olga Krafcsik, Zsolt Czigány, Sándor Lenk, David Beke, Adam Gali
In this study, we implement thiol termination on the surface of few-nanometer-sized silicon carbide (SiC) nanoparticles (NPs) to enable further applications, such as fluorescent biomarkers. Various spectroscopic techniques are employed to monitor the effectiveness of the surface treatment. Additionally, a thiol-Michael addition reaction is performed by conjugating 4-arm PEG-maleimide molecules to the thiol groups of SiC NPs, further demonstrating the reactivity of thiol-terminated SiC NPs. These thiolated SiC NPs, both with and without conjugated molecules, open new avenues in biotechnology.
Materials Science (cond-mat.mtrl-sci)
13 pages, 6 figures, 4 tables
Highly efficient field-free switching by orbital Hall torque in a MoS2-based device operating at room temperature
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-13 20:00 EST
Antonio Bianco, Michele Ceccardi, Raimondo Cecchini, Daniele Marre', Chanchal K. Barman, Fabio Bernardini, Alessio Filippetti, Federico Caglieris, Ilaria Pallecchi
Charge-to-spin and spin-to-charge conversion mechanisms in high spin-orbit materials are the new frontier of memory devices. They operate via spin-orbit torque (SOT) switching of a magnetic electrode, driven by an applied charge current. In this work, we propose a novel memory device based on the semiconducting two-dimensional centrosymmetric transition metal dichalcogenide (TMD) MoS2, that operates as a SOT device in the writing process and a spin valve in the reading process. We demonstrate that stable voltage states at room temperature can be deterministically controlled by a switching current density as low as 3.2x10^4 A/cm^2 even in zero field. An applied field 50-100 Oe can be used as a further or alternative control parameter for the state switching. Ab initio calculations of spin Hall effect (SHE) and orbital Hall effect (OHE) indicate that the latter is the only one responsible for the generation of the SOT in the magnetic electrode. The large value of OHC in bulk MoS2 makes our device competitive in terms of energetic efficiency and could be integrated in TMD heterostructures to design memory devices with multiple magnetization states for non-Boolean computation.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
On the crystalline environment of luminescent Tb\(^{3+}\) ions embedded in indium tin oxide thin films: a DFT and Crystal field analysis assessment
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
E. Serquen, K. Lizárraga, L. A. Enrique, F. Bravo, S. Mishra, P. LLontop, P. Venezuela, L. R. Tessler, J. A. Guerra
We assess the local symmetry and crystal environment of trivalent terbium ions embedded in an indium tin oxide (ITO) matrix with bixbyite structure. The ions tend to substitute ions in two different cationic sites (\(b\) and \(d\)). Density Functional Theory (DFT) calculations suggest that the ions are mainly located at \(C_2\) symmetry sites relaxing selection rules and enabling electric dipole transitions, with the \(^5\text{D}_4\rightarrow\leftindex^7{\text{F}}_2\) transition being the most intense, providing a red color to the light emission. Photoluminescence emission spectra under UV excitation at revealed 30 intra-4\(f\) transitions, which were assigned to the \(\leftindex^7{\text{F}}_J\) ground multiplet of the ion. Crystal-field analysis shows a strong alignment between calculated and observed energy levels, yielding a standard deviation of \(\sigma=\qty{15.1}{\centi\per\metre}\). We believe these results can help to understand the activation mechanisms of luminescent centers in transparent conductive oxides, as well as the potential to modulate emission color through its crystalline environment.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
8 pages, 4figures
A comprehensive approach to incorporating intermolecular dispersion into the openCOSMO-RS model. Part 2: Atomic polarizabilities
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-13 20:00 EST
Daria Grigorash, Simon Müller, Esther Heid, Frank Neese, Dimitrios Liakos, Christoph Riplinger, Miquel García-Ratés, Patrice Paricaud, Erling H. Stenby, Irina Smirnova, Wei Yan
openCOSMO-RS is an open-source predictive thermodynamic model that can be applied to a broad range of systems in various chemical and biochemical engineering domains. This study focuses on improving openCOSMO-RS by introducing a new dispersion term based on atomic polarizabilities. We evaluate different methods for processing polarizability data, including scaling and combining it to compute segment-segment dispersion interaction energies, with a focus on halocarbon systems. The results demonstrate that the modified model outperforms our previous method developed in the first part of this work (Grigorash et al., 2024) , while at the same time requiring fewer adjustable parameters. The approach was applied to a broad dataset of over 50,000 data points, consistently increasing the accuracy across a variety of data types. These findings suggest that atomic polarizability is a valuable descriptor for refining dispersion interactions in predictive thermodynamic models.
Soft Condensed Matter (cond-mat.soft)
Fine-Tuning Exciton Polaron Characteristics via Lattice Engineering in 2D Hybrid Perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Katherine A Koch, Martin Gomez-Dominguez, Esteban Rojas-Gatjens, Alexander Evju, K Burak Ucer, Juan-Pablo Correa-Baena, Ajay Ram Srimath Kandada
The layered structure of 2D metal halide perovskites (MHPs) consisting of an ionic metal halide octahedral layer electronically separated by an organic cation, exhibits strong coupling between high-binding-energy excitons and low-energy lattice phonons. Photoexcitations in these systems are believed to be exciton polarons, Coulombically bound electron-hole pairs dressed by lattice vibrations. Understanding and controlling the structural and chemical factors that govern this interaction is crucial for optimizing exciton recombination, transport, and many-body interactions. Our study examines the role of the organic cation in a prototypical 2D-MHP system, phenylethylammonium lead iodide, (PEA)2PbI4, and its halogenated derivatives, (F/Cl-PEA)2PbI4. These substitutions allow us to probe polaronic effects while maintaining the average lattice and electronic structure. Using resonant impulsive stimulated Raman scattering (RISRS), we analyze the metal-halide sub-lattice motion coupled to excitons. We apply formalism based on a perturbative expansion of the nonlinear response function on the experimental data to estimate the Huang-Rhys parameter, \(S=1/2 \Delta^2\), to quantify the lattice displacement (\(\Delta\)) due to exciton-phonon coupling. A direct correlation emerges between lattice displacement and octahedral distortion, with F-PEA exhibiting the largest shift and Cl-PEA exhibiting the least, significantly influencing the fine structure features in absorption. Additionally, 2D electronic spectroscopy reveals that F-PEA, with the strongest polaronic coupling, exhibits the least thermal dephasing, supporting the polaronic protection hypothesis. Our findings suggest that systematic organic cation substitution serves as a tunable control for the fine structure in 2D-MHPs, and offers a pathway to mitigate many-body scattering effects by tailoring the polaronic coupling.
Materials Science (cond-mat.mtrl-sci)
Microscopic Origin of Reduced Magnetic Order in a Metallic Host
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-13 20:00 EST
X. Boraley, O. Stockert, J. Lass, R. Sibille, Ø. S. Fjellvåg, S. Moody, A. M. Läuchli, V. Fritsch, D. G. Mazzone
Although magnetic frustration in metals provides a promising avenue for novel quantum phenomena, their microscopic interpretation is often challenging. Here we use the face-centered cubic intermetallic HoInCu\(_4\) as model material to show that Hamiltonians neglecting the charge degree of freedom are appropriate for frustrated metals possessing low density of states at the Fermi surface. Through neutron scattering techniques we determine matching magnetic exchange interactions in the paramagnetic and field-polarized states using an effective spin-1 Heisenberg Hamiltonian, for which we identify antiferromagnetic nearest and next-nearest neighbour interactions \(J_1\) and \(J_2\) that are close to the critical ratio \(J_2\)/\(J_1\) = 1/2. The study further provides evidence that spin-wave theory fails to predict the low-energy spin dynamics in the antiferromagnetic zero-field state, which is dominated by overdamped magnetic excitations. We conclude that the low-energy fluctuations arise from quantum fluctuations, accounting for the missing moment of the strongly renormalized magnetic long-range order.
Strongly Correlated Electrons (cond-mat.str-el)
A universal route from avalanches in mean-field models with random fields to stochastic Poisson branching events
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-13 20:00 EST
Avalanches in mean-field models can be mapped to memoryless branching processes defining a universality class. We present a reduced expression mapping a broad family of critical and subcriticial avalanches in mean-field models at the thermodynamic limit to rooted trees in a memoryless Poisson branching processes with random occurrence times. We derive the exact mapping for the athermal random field Ising model and the democratic fiber bundle model, where avalanche statistics progress towards criticality, and as an approximation for the self-organized criticality in slip mean-field theory. Avalanche dynamics and statistics in the three models differ only on the evolution of the field density, interaction strength, and the product of both terms determining the branching number.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech), Adaptation and Self-Organizing Systems (nlin.AO)
6 pages, 3 figures
Non-Reciprocal Current-Phase Relation and Superconducting Diode Effect in Topological-Insulator-Based Josephson Junctions
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-13 20:00 EST
A. Kudriashov, X. Zhou, R.A. Hovhannisyan, A. Frolov, L. Elesin, Y. Wang, E.V. Zharkova, T. Taniguchi, K. Watanabe, L.A. Yashina, Z. Liu, Xin Zhou, K.S. Novoselov, D.A. Bandurin
Josephson junctions (JJ) are essential for superconducting quantum technologies and searches of self-conjugate quasiparticles, pivotal for fault-tolerant quantum computing. Measuring the current-phase relation (CPR) in JJ based on topological insulators (TI) can provide critical insights into unconventional phenomena in these systems, such as the presence of Majorana bound states (MBS) and the nature of non-reciprocal transport. However, reconstructing CPR as a function of magnetic field in such JJs has remained experimentally challenging. Here, we introduce a platform for precise CPR measurements in planar JJs composed of NbSe\(_2\) and few layer thick Bi\(_2\)Se\(_3\) (TI) as a function of magnetic field. When a single flux quantum \(\Phi_\mathrm{0}\) threads the junction, we observe anomalous peak-dip-shaped CPR behaviour and non-reciprocal supercurrent flow. We demonstrate that these anomalies stem from the edge-amplified sloped supercurrent profile rather than MBS signatures often invoked to explain puzzles emerging near \(\Phi_\mathrm{0}\) in TI-based JJ. Furthermore, we show that such a supercurrent profile gives rise to a previously overlooked, robust and tunable Josephson diode effect. These findings establish field-dependent CPR measurements as a critical tool for exploring topological superconducting devices and offer new design principles for non-reciprocal superconducting electronics.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 5 figures
Broken symmetries associated with a Kagome chiral charge order
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-13 20:00 EST
Zi-Jia Cheng, Md Shafayat Hossain, Qi Zhang, Sen Shao, Jinjin Liu, Yilin Zhao, Mohammad Yahyavi, Yu-Xiao Jiang, Jia-Xin Yin, Xian Yang, Yongkai Li, Tyler A. Cochran, Maksim Litskevich, Byunghoon Kim, Junyi Zhang, Yugui Yao, Luis Balicas, Zhiwei Wang, Guoqing Chang, M. Zahid Hasan
Chirality or handedness manifests in all fields of science, ranging from cell biology, molecular interaction, and catalysis to different branches of physics. In condensed matter physics, chirality is intrinsic to enigmatic quantum phases, such as chiral charge density waves and chiral superconductivity. Here, the underlying chiral response is subtle and leads to broken symmetries in the ground state. Detection of subtle broken symmetries is the key to understand these quantum states but they are extremely challenging to expose leading to debate and controversy. Here, using second-order optical response, we uncover the broken symmetries of a chiral charge density wave in the Kagome lattice KV3Sb5, revealing the relevant broken symmetries of its charge order. KV3Sb5 undergoes a phase transition to a charge-ordered state at low temperatures. Our polarization-dependent mid-infrared photocurrent microscopy reveals an intrinsic, longitudinal helicity-dependent photocurrent associated with the charge order. Our measurements, supported by our theoretical analysis, provide direct evidence for broken inversion and mirror symmetries at the charge order transition, indicating a chiral charge ordered state. On the other hand, we do not observe a circular photogalvanic effect along the direction perpendicular to that of the incident light, imposing stringent constraints on the rotational and point group symmetries of the charge order. Our study not only visualizes the chiral nature of the Kagome charge order revealing its broken symmetries, but also highlights the nonlinear photogalvanic effect as a sensitive probe for detecting subtle symmetry breakings.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
in press
Nature Communications (2025)
Improved Calculation of Acoustic Deformation Potentials from First Principles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Patrick Williams, Angela Dyson
Using density functional theory (DFT) and density functional perturbation theory (DFPT), the band structure, phonon dispersion and electron phonon coupling matrix were calculated for silicon (Si), diamond and cubic boron nitride (cBN). From these, the acoustic deformation potential was calculated for multiple angles between the electron and phonon wave vectors and analytic expressions for the longitudinal and acoustic modes were fit to find an average deformation potential. The ability to calculate the deformation potential from first principles allows for the scattering rates to be determined without the use of lengthy empirical methods. For Si, the numerically calculated deformation potentials are in excellent agreement with what is seen in the literature. On the other hand, the deformation potentials calculated for diamond were found to be larger than what has been seen previously, however previous calculations of transport parameters in diamond report a large range of values for scattering parameters which may be due to assumptions made in each model. Excellent agreement was also seen between the value calculated for cBN and the literature, however there are no experimental results for cBN and so this value is compared against an estimate. This shows that scattering parameters can be calculated via first principles for materials with sparse experimental data, which in turn allows for increased confidence in the output of charge transport simulations of new and emerging materials.
Materials Science (cond-mat.mtrl-sci)
10 Pages, 6 figures, to be published
Interacting Particle Systems Modeling Self-Propelled Motions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-13 20:00 EST
Saori Morimoto, Makoto Katori, Hiraku Nishimori
In non-equilibrium statistical physics, active matters in both living and non-living systems have been extensively studied. In particular, self-propelled particle systems provide challenging research subjects in experimental and theoretical physics, since individual and collective behaviors of units performing persistent motions can not be described by usual fluctuation theory for equilibrium systems. A typical example of man-made self-propelled systems which can be easily handled in small-sized experiments is a system of camphor floats put on the surface of water. Based on the experimental and theoretical studied by Nishimori et al. (J. Phys. Soc. Jpn. 86 (2017) 101012), we propose a new type of mathematical models for complex motions of camphor disks on the surface of water. In the previous mathematical models introduced by Nishimori et al. are coupled systems of the equations of motion for camphor disks described by ordinary differential equations and the partial differential equation for the concentration field of camphor molecules in water. Here we consider coupled systems of equation of motions of camphor disks and random walks representing individual camphor molecules in water. In other words, we take into account non-equilibrium fluctuations by introducing stochastic processes into the deterministic models. Numerical simulation shows that our models can represent self-propelled motions of individual camphor disk as well as repulsive interactions among them. We focus on the one-dimensional models in which viscosity is dominant, and derive a dynamical system of a camphor disk by taking the average of random variables of our stochastic system. By studying both of stochastic models and dynamical systems, we clarify the transitions between three phases of motions for a camphor disk depending on parameters.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Adaptation and Self-Organizing Systems (nlin.AO)
LaTeX 18 pages, 8 figures
Monolayer transition metal dichalcogenides under finite-pulse polarized radiation
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-13 20:00 EST
Alejandro S. Gómez, Yuriko Baba, Francisco Domínguez-Adame, Rafael A. Molina
Recent advances in time-resolved angle-resolved photoemission spectroscopy have enabled access to ultrafast electron states and their spin dynamics in solids. Atomically thin transition metal dichalcogenides are paradigmatic two-dimensional materials where electron momentum and spin degrees of freedom are coupled, being suitable candidates for time-resolved spectroscopy studies. In this work, we present a thorough study of the electron dynamics when these materials are subject to an intense finite-pulse driving radiation. We extend the scope of the conventional Floquet engineering and rely of the so-called \(t-t^{\prime}\) formalism to deal with driving fields described with two distinct time scales, namely the envelope amplitude timescale and the time period of the external field. The interplay between the finite-pulse timescales and the intrinsic properties of the electrons gives rise to transient valley polarization and dynamical modifications of band structures, revealed by the time-dependent circular dichroism of the sample.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
17 pages, 12 figures
Ferri- and Ferro-Electric Switching in Spontaneously Chiral Polar Liquid Crystals
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-13 20:00 EST
Jordan Hobbs, Calum J. Gibb, Richard J. Mandle
The recent discovery of spontaneous chiral symmetry breaking has demonstrated the possibility of discovering the exotic textures of ferromagnetic systems in liquid crystalline fluid ferro-electrics. We show that the polar smectic mesophase exhibited by the first molecule discovered to exhibit a spontaneously chiral ferroelectric nematic phase is also helical has a strongly varied textural morphology depending in its thermal history and phase ordering. Electro-optic studies demonstrate that the two spontaneously chiral phases exhibit field induced phase transitions. For the nematic variant, this process is threshold-less and has no hysteresis while for the smectic it has a clear threshold and shows hysteresis meaning this phase exhibits pseudo-ferrielectric switching, the first of its kind for ferroelectric nematic like phases. We show that helix formation can be both 1st and 2nd order but when it is 1st it is accompanied by pre-transitional helix formation in the preceding ferroelectric nematic phase.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Phenothiazine-Based Self-Assembled Monolayer with Thiophene Head Groups Minimizes Buried Interface Losses in Tin Perovskite Solar Cells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Valerio Stacchini, Madineh Rastgoo, Mantas Marčinskas, Chiara Frasca, Kazuki Morita, Lennart Frohloff, Antonella Treglia, Orestis Karalis, Vytautas Getautis, Annamaria Petrozza, Norbert Koch, Hannes Hempel, Tadas Malinauskas, Antonio Abate, Artem Musiienko
Self-assembled monolayers (SAMs) have revolutionized the fabrication of lead-based perovskite solar cells, but they remain underexplored in tin perovskite systems. PEDOT is the material of choice for hole-selective layers in tin perovskite solar cells (TPSCs), but presents challenges for both performance and stability. MeO-2PACz, the only SAM reported for Sn perovskites, enables device fabrication but consistently underperforms when compared to PEDOT. In this work, we identify that MeO-2PACz's limitations arise from excessively strong interactions with perovskite surface and poor lattice matching, leading to poor interface quality. To overcome these issues, we design, synthesize, and characterize a novel SAM-forming molecule called Th-2EPT. Th-2EPT optimizes coordination strength and improves lattice compatibility, contributing to the creation of a high-quality buried interface and dramatically suppressing non-radiative recombination. We used Density Functional Theory (DFT) to evaluate coordination strength and lattice compatibility, complemented by nanosecond-resolution optical characterization techniques to confirm significantly reduced interfacial recombination and enhanced carrier lifetimes in Th-2EPT-Perovskite films. With Th-2EPT, we demonstrated the first SAM-based tin perovskite solar cells to outperform PEDOT-based devices, delivering a record power conversion efficiency (PCE) of 8.2% with a DMSO-free solvent system.
Materials Science (cond-mat.mtrl-sci)
Submitted
Chasing Charge Carriers: Diffusion Dynamics in Mixed-n Quasi-Two-Dimensional Colloidal MAPbBr3 Perovskites
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Ronja Maria Piehler, Eugen Klein, Francisco M. Gomez-Campos, Oliver Kühn, Rostyslav Lesyuk, Christian Klinke
In optoelectronic applications, metal halide perovskites (MHPs) are compelling materials because of their highly tuneable and intensely competitive optical properties. Colloidal synthesis enables the controlled formation of various morphologies of MHP nanocrystals, all with different carrier properties and, hence, different optical and carrier transport behaviours. We characterized three different methylammonium lead tribromide perovskite (MAPbBr3) morphologies: nanoplatelets (NPLs), nanosheets (NSs), and nanostripes (NSTs) synthesized by hot-injection synthesis protocols with slightly different parameters. A fluorescence imaging microscope (FLIM) for time- and space-resolved measurements of the carrier migration was employed to quantify the charge carriers' migration process upon photoexcitation. The results are rationalized in the two-dimensional diffusion model framework, considering funnelling and trapping processes in mixed-n colloidal MHPs. Subdiffusion mode was found to prevail in the nanocrystals, whereby the highest carrier diffusivity was found for bulk-like NSTs, followed by layered NSs and a film of NPLs. These findings provide a better understanding of optoelectronic processes in perovskites relevant to photovoltaic and light-emitting devices.
Materials Science (cond-mat.mtrl-sci)
14 pages, 6 figures
Stretching Response of a Polymer Chain with Deformable Bonds
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-13 20:00 EST
The stretching response of polymer chains fundamentally determines the mechanical properties of polymer networks. In this work, we develop a statistical mechanics model that incorporates both bond stretching and bond angle deformation, enabling accurate predictions of chain behavior up to large forces. This model achieves excellent agreement with experimental data for carbon chains across all force regimes using physical parameters only. We further propose a semi-analytical deformable Freely Rotating Chain (dFRC) model, which represents the chain as a freely rotating chain with effective bond stretch and bond angle that depend on the chain stretch. We show that the dFRC model is accurate over the entire force range using the same physical parameters as the statistical model without fitting. Additionally, the dFRC model provides a direct estimate of the bond force, which is crucial to predict chain scission. By capturing key bond deformations while remaining computationally efficient, our work lays the foundation for future modeling of polymer network elasticity and failure.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
32 pages, 24 figures
Nanoscale Mapping of Magnetic Orientations with Complex X-ray Magnetic Linear Dichroism
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-13 20:00 EST
Marina Raboni Ferreira, Benedikt J. Daurer, Jeffrey Neethirajan, Andreas Apseros, Sandra Ruiz-Gómez, Burkhard Kaulich, Majid Kazemian, Claire Donnelly
Compensated magnets are of increasing interest for both fundamental research and applications, with their net-zero magnetization leading to ultrafast dynamics and robust order. To understand and control this order, nanoscale mapping of local domain structures is necessary. One of the main routes to mapping antiferromagnetic order is X-ray magnetic linear dichroism (XMLD), which probes the local orientation of the Néel vector. However, XMLD imaging typically suffers from weak contrast and has mainly been limited to surface-sensitive techniques. Here, we harness coherent diffractive imaging to map the complex XMLD spectroscopically, and identify the phase linear dichroism as a high-contrast, high-resolution mechanism for imaging magnetic order. By applying X-ray spectroptychography to a model sample, we retrieve the full complex XMLD spectrum. Combining this with hierarchical clustering, we resolve the spatial distribution of probed domains by their distinct spectral signatures, providing a robust method for analyzing magnetic configurations with weak signals. Our results show that phase contrast is significantly stronger than the corresponding absorption contrast, offering higher spatial-resolution magnetic imaging. This approach establishes a reliable, element- and orbital-sensitive tool for studying compensated magnets.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Triggered ferroelectricity in HfO\(_2\) from polar hybrid zone-boundary phonon instability
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-13 20:00 EST
Ferroelectric HfO\(_2\) has garnered significant attention for its promising application in high density nonvolatile data storage and nanoscale transistors. However, the uncertain origin of polarization in HfO\(_2\) limits our ability to fully understand and control its ferroelectricity. The ongoing debate centers on whether HfO\(_2\) is a proper or improper ferroelectric, as it exhibits characteristics of both types. In this study, we utilize symmetry-guided first-principles quantum mechanical (DFT) calculations to accurately map the energy landscape and identify the coherent switching pathway of HfO\(_2\) by voltage. Our findings reveal two key insights. First, ferroelectricity in HfO\(_2\) is driven by a triggered mechanism through coupling between the stable polar mode and hybrid non-polar modes. Second, unusually high polarization arises from the hybrid modes, which consists solely of non-polar modes. The results fundamentally transforms the perspective on polarization in HfO\(_2\) and resolve conflicting characteristics observed, offering valuable guidance for superior technological applications.
Materials Science (cond-mat.mtrl-sci)
Superconductivity of Bad Fermions: Origin of Two Gaps in HTSC Cuprates
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-13 20:00 EST
E.A. Stepanov, S. Iskakov, M.I. Katsnelson, A.I. Lichtenstein
We investigate the spectral properties of the doped \({t-t'}\) Hubbard model with parameters typical for high-temperature cuprate superconductors. Our approach is based on a novel strong-coupling Green's function expansion around a reference system -- the exactly solvable undoped particle-hole symmetric Hubbard lattice -- that possesses a large antiferromagnetic Mott-Hubbard-Slater gap in the electron spectrum. The electron spectral function in the case of a large next-nearest-neighbor hopping \({t'=-0.3t}\), which is characteristic of the \({T_c \approx 100\,\text{K}}\) family of cuprates, reveals a strongly renormalized flat band feature with a pseudogap around the antinodal point. The superconducting response of this system to a small \({d_{x^2-y^2}}\)-like external field exhibits a very unusual form. It features a pseudogap at the antinodal point in the normal part of the Nambu Green's function, related to a ``bad-fermion'' behavior in a normal phase, as well as a \({d}\)-wave-like structure in the anomalous (Gorkov's) Green's function, with zero response at the nodal point of the Brillouin zone. Remarkably, we find that the anomalous part of the response deviates essentially from the simplest \({(\cos{k_x}-\cos{k_y})}\) form in momentum space. Specifically, its extrema are shifted away from the \({(\pi,0)}\) and \({(0,\pi)}\) points due to suppression of the response by the pseudogap. The observed two-gap structure of the electron spectra in a generic strong-coupling model of cuprates can serve as a basis for phenomenological treatment of different physical properties of high-temperature superconductors within two-fluid model.
Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 10 figures