CMP Journal 2025-03-07
Statistics
Nature Materials: 3
Science: 6
arXiv: 79
Nature Materials
A facile approach for generating ordered oxygen vacancies in metal oxides
Original Paper | Design, synthesis and processing | 2025-03-06 19:00 EST
Kexin Chen, Xuanyi Yuan, Zhaobo Tian, Mingchu Zou, Yifei Yuan, Zhanglin Chen, Qinghua Zhang, YuYang Zhang, Xin Jin, Tianpin Wu, Reza Shahbazian-Yassar, Guanghua Liu
Oxygen vacancies in oxide materials, although demonstrated to be beneficial for many applications, are hard to be generated and manipulated as desired, particularly for bulk materials with a large size and limited surface area. Here, by simply coupling the thermal activation with a simultaneously applied electric field, we efficiently generate ordered oxygen vacancies within bulk crystals of ternary SrAl2O4, binary TiO2 and other common oxide materials, which give rise to superior functionalities. We expect that this approach offers a general and practical way for the vacancy engineering of oxide materials and holds great promise for their applications.
Design, synthesis and processing, Materials science
Vapour-liquid-solid-solid growth of two-dimensional non-layered β-Bi2O3 crystals with high hole mobility
Original Paper | Electronic devices | 2025-03-06 19:00 EST
Yunhai Xiong, Duo Xu, Yousheng Zou, Lili Xu, Yujie Yan, Jianghua Wu, Chen Qian, Xiufeng Song, Kairui Qu, Tong Zhao, Jie Gao, Jialin Yang, Kai Zhang, Shengli Zhang, Peng Wang, Xiang Chen, Haibo Zeng
Currently, p-type two-dimensional (2D) materials lag behind n-type ones in both quantity and performance, hindering their use in advanced p-channel transistors and complementary logic circuits. Non-layered materials, which make up 95% of crystal structures, hold the potential for superior p-type 2D materials but remain challenging to synthesize. Here we show a vapour-liquid-solid-solid growth of atomically thin (<1 nm), high-quality, non-layered 2D β-Bi2O3 crystals on a SiO2/Si substrate. These crystals form via a transformation from layered BiOCl intermediates. We further realize 2D β-Bi2O3 transistors with room-temperature hole mobility and an on/off current ratio of 136.6 cm2 V-1 s-1 and 1.2 × 108, respectively. The p-type nature is due to the strong suborbital hybridization of Bi 6s26p3 with O 2p4 at the crystal’s M-point valence band maximum. Our work can be used as a reference that adds more 2D non-layered materials to the 2D toolkit and shows 2D β-Bi2O3 to be promising candidate for future electronics.
Electronic devices, Electronic properties and materials, Structural properties, Synthesis and processing, Two-dimensional materials
Stiff and self-healing hydrogels by polymer entanglements in co-planar nanoconfinement
Original Paper | Nanoscale materials | 2025-03-06 19:00 EST
Chen Liang, Volodymyr Dudko, Olena Khoruzhenko, Xiaodan Hong, Zhong-Peng Lv, Isabell Tunn, Muhammad Umer, Jaakko V. I. Timonen, Markus B. Linder, Josef Breu, Olli Ikkala, Hang Zhang
Many biological tissues are mechanically strong and stiff but can still heal from damage. By contrast, synthetic hydrogels have not shown comparable combinations of properties, as current stiffening approaches inevitably suppress the required chain/bond dynamics for self-healing. Here we show a stiff and self-healing hydrogel with a modulus of 50 MPa and tensile strength up to 4.2 MPa by polymer entanglements in co-planar nanoconfinement. This is realized by polymerizing a highly concentrated monomer solution within a scaffold of fully delaminated synthetic hectorite nanosheets, shear oriented into a macroscopic monodomain. The resultant physical gels show self-healing efficiency up to 100% despite the high modulus, and high adhesion shear strength on a broad range of substrates. This nanoconfinement approach allows the incorporation of novel functionalities by embedding colloidal materials such as MXenes and can be generalized to other polymers and solvents to fabricate stiff and self-healing gels for soft robotics, additive manufacturing and biomedical applications.
Nanoscale materials, Soft materials
Science
Tropical forests in the Americas are changing too slowly to track climate change
Research Article | Forest change | 2025-03-07 03:00 EST
Jesús Aguirre-Gutiérrez, Sandra Díaz, Sami W. Rifai, Jose Javier Corral-Rivas, Maria Guadalupe Nava-Miranda, Roy González-M, Ana Belén Hurtado-M, Norma Salinas Revilla, Emilio Vilanova, Everton Almeida, Edmar Almeida de Oliveira, Esteban Alvarez-Davila, Luciana F. Alves, Ana Cristina Segalin de Andrade, Antonio Carlos Lola da Costa, Simone Aparecida Vieira, Luiz Aragão, Eric Arets, Gerardo A Aymard C., Fabrício Baccaro, Yvonne Vanessa Bakker, Timothy R. Baker, Olaf Bánki, Christopher Baraloto, Plínio Barbosa de Camargo, Erika Berenguer, Lilian Blanc, Damien Bonal, Frans Bongers, Kauane Maiara Bordin, Roel Brienen, Foster Brown, Nayane Cristina C. S. Prestes, Carolina V. Castilho, Sabina Cerruto Ribeiro, Fernanda Coelho de Souza, James A. Comiskey, Fernando Cornejo Valverde, Sandra Cristina Müller, Richarlly da Costa Silva, Julio Daniel do Vale, Vitor de Andrade Kamimura, Ricardo de Oliveira Perdiz, Jhon del Aguila Pasquel, Géraldine Derroire, Anthony Di Fiore, Mathias Disney, William Farfan-Rios, Sophie Fauset, Ted R. Feldpausch, Rafael Flora Ramos, Gerardo Flores Llampazo, Valéria Forni Martins, Claire Fortunel, Karina Garcia Cabrera, Jorcely Gonçalves Barroso, Bruno Hérault, Rafael Herrera, Eurídice N. Honorio Coronado, Isau Huamantupa-Chuquimaco, John J. Pipoly, Katia Janaina Zanini, Eliana Jiménez, Carlos A. Joly, Michelle Kalamandeen, Joice Klipel, Aurora Levesley, Wilmar Lopez Oviedo, William E. Magnusson, Rubens Manoel dos Santos, Beatriz Schwantes Marimon, Ben Hur Marimon-Junior, Simone Matias de Almeida Reis, Omar Aurelio Melo Cruz, Abel Monteagudo Mendoza, Paulo Morandi, Robert Muscarella, Henrique Nascimento, David A. Neill, Imma Oliveras Menor, Walter A. Palacios, Sonia Palacios-Ramos, Nadir Carolina Pallqui Camacho, Guido Pardo, R. Toby Pennington, Luciana de Oliveira Pereira, Georgia Pickavance, Rayana Caroline Picolotto, Nigel C. A. Pitman, Adriana Prieto, Carlos Quesada, Hirma Ramírez-Angulo, Maxime Réjou-Méchain, Zorayda Restrepo Correa, José Manuel Reyna Huaymacari, Carlos Reynel Rodriguez, Gonzalo Rivas-Torres, Anand Roopsind, Agustín Rudas, Beatriz Salgado Negret, Masha T. van der Sande, Flávia Delgado Santana, Flavio Antonio Maës Santos, Rodrigo Scarton Bergamin, Miles R. Silman, Camila Silva, Javier Silva Espejo, Marcos Silveira, Fernanda Cristina Souza, Martin J. P. Sullivan, Varun Swamy, Joey Talbot, John J. Terborgh, Peter J. van der Meer, Geertje van der Heijden, Bert van Ulft, Rodolfo Vasquez Martinez, Laura Vedovato, Jason Vleminckx, Vincent Antoine Vos, Verginia Wortel, Pieter A. Zuidema, Joeri A. Zwerts, Susan G. W. Laurance, William F. Laurance, Jerôme Chave, James W. Dalling, Jos Barlow, Lourens Poorter, Brian J. Enquist, Hans ter Steege, Oliver L. Phillips, David Galbraith, Yadvinder Malhi
Understanding the capacity of forests to adapt to climate change is of pivotal importance for conservation science, yet this is still widely unknown. This knowledge gap is particularly acute in high-biodiversity tropical forests. Here, we examined how tropical forests of the Americas have shifted community trait composition in recent decades as a response to changes in climate. Based on historical trait-climate relationships, we found that, overall, the studied functional traits show shifts of less than 8% of what would be expected given the observed changes in climate. However, the recruit assemblage shows shifts of 21% relative to climate change expectation. The most diverse forests on Earth are changing in functional trait composition but at a rate that is fundamentally insufficient to track climate change.
Neonatal fungi promote lifelong metabolic health through macrophage-dependent β cell development
Research Article | Microbiota | 2025-03-07 03:00 EST
Jennifer Hampton Hill, Rickesha Bell, Logan Barrios, Halli Baird, Kyla Ost, Morgan Greenewood, Josh K. Monts, Erin Tracy, Casey H. Meili, Tyson R. Chiaro, Allison M. Weis, Karen Guillemin, Anna E. Beaudin, L. Charles Murtaugh, W. Zac Stephens, June L. Round
Loss of early-life microbial diversity is correlated with diabetes, yet mechanisms by which microbes influence disease remain elusive. We report a critical neonatal window in mice when microbiota disruption results in lifelong metabolic consequences stemming from reduced β cell development. We show evidence for the existence of a similar program in humans and identify specific fungi and bacteria that are sufficient for β cell growth. The microbiota also plays an important role in seeding islet-resident macrophages, and macrophage depletion during development reduces β cells. Candida dubliniensis increases β cells in a macrophage-dependent manner through distinctive cell wall composition and reduces murine diabetes incidence. Provision of C. dubliniensis after β cell ablation or antibiotic treatment improves β cell function. These data identify fungi as critical early-life commensals that promote long-term metabolic health.
Macrophage peroxisomes guide alveolar regeneration and limit SARS-CoV-2 tissue sequelae
Research Article | Coronavirus | 2025-03-07 03:00 EST
Xiaoqin Wei, Wei Qian, Harish Narasimhan, Ting Chan, Xue Liu, Mohd Arish, Samuel Young, Chaofan Li, In Su Cheon, Qing Yu, Gislane Almeida-Santos, Xiao-Yu Zhao, Eric V. Yeatts, Olivia J. Spear, Megan Yi, Tanyalak Parimon, Yinshan Fang, Young S. Hahn, Timothy N. J. Bullock, Lindsay A. Somerville, Mark H. Kaplan, Anne I. Sperling, Yun Michael Shim, Robert Vassallo, Peter Chen, Sarah E. Ewald, Anja C. Roden, Jianwen Que, Dianhua Jiang, Jie Sun
Peroxisomes are vital but often overlooked metabolic organelles. We found that excessive interferon signaling remodeled macrophage peroxisomes. This loss of peroxisomes impaired inflammation resolution and lung repair during severe respiratory viral infections. Peroxisomes were found to modulate lipid metabolism and mitochondrial health in a macrophage type-specific manner and enhanced alveolar macrophage-mediated tissue repair and alveolar regeneration after viral infection. Peroxisomes also prevented excessive macrophage inflammasome activation and IL-1β release, limiting accumulation of KRT8high dysplastic epithelial progenitors following viral injury. Pharmacologically enhancing peroxisome biogenesis mitigated both acute symptoms and post-acute sequelae of COVID-19 (PASC) in animal models. Thus, macrophage peroxisome dysfunction contributes to chronic lung pathology and fibrosis after severe acute respiratory syndrome coronavirus 2 infection.
G-quadruplex-stalled eukaryotic replisome structure reveals helical inchworm DNA translocation
Research Article | Molecular biology | 2025-03-07 03:00 EST
Sahil Batra, Benjamin Allwein, Charanya Kumar, Sujan Devbhandari, Jan-Gert Brüning, Soon Bahng, Chong M. Lee, Kenneth J. Marians, Richard K. Hite, Dirk Remus
DNA G-quadruplexes (G4s) are non-B-form DNA secondary structures that threaten genome stability by impeding DNA replication. To elucidate how G4s induce replication fork arrest, we characterized fork collisions with preformed G4s in the parental DNA using reconstituted yeast and human replisomes. We demonstrate that a single G4 in the leading strand template is sufficient to stall replisomes by arresting the CMG helicase. Cryo-electron microscopy structures of stalled yeast and human CMG complexes reveal that the folded G4 is lodged inside the central CMG channel, arresting translocation. The G4 stabilizes the CMG at distinct translocation intermediates, suggesting an unprecedented helical inchworm mechanism for DNA translocation. These findings illuminate the eukaryotic replication fork mechanism under normal and perturbed conditions.
Historic manioc genomes illuminate maintenance of diversity under long-lived clonal cultivation
Research Article | Crop genetics | 2025-03-07 03:00 EST
Logan Kistler, Fabio de Oliveira Freitas, Rafal M. Gutaker, S. Yoshi Maezumi, Jazmín Ramos-Madrigal, Marcelo F. Simon, J. Moises Mendoza F., Sergei V. Drovetski, Hope Loiselle, Eder Jorge de Oliveira, Eduardo Alano Vieira, Luiz Joaquim Castelo Branco Carvalho, Marina Ellis Perez, Audrey T. Lin, Hsiao-Lei Liu, Rachel Miller, Natalia A. S. Przelomska, Aakrosh Ratan, Nathan Wales, Kevin Wann, Shuya Zhang, Magdalena García, Daniela Valenzuela, Francisco Rothhammer, Calogero M. Santoro, Alejandra I. Domic, José M. Capriles, Robin G. Allaby
Manioc–also called cassava and yuca–is among the world’s most important crops, originating in South America in the early Holocene. Domestication for its starchy roots involved a near-total shift from sexual to clonal propagation, and almost all manioc worldwide is now grown from stem cuttings. In this work, we analyze 573 new and published genomes, focusing on traditional varieties from the Americas and wild relatives from herbaria, to reveal the effects of this shift to clonality. We observe kinship over large distances, maintenance of high genetic diversity, intergenerational heterozygosity enrichment, and genomic mosaics of identity-by-descent haploblocks that connect all manioc worldwide. Interviews with Indigenous traditional farmers in the Brazilian Cerrado illuminate how traditional management strategies for sustaining, diversifying, and sharing the gene pool have shaped manioc diversity.
A subcellular map of translational machinery composition and regulation at the single-molecule level
Research Article | Cell biology | 2025-03-07 03:00 EST
Zijian Zhang, Adele Xu, Yunhao Bai, Yuxiang Chen, Kitra Cates, Craig Kerr, Abel Bermudez, Teodorus Theo Susanto, Kelsie Wysong, Fernando J. García Marqués, Garry P. Nolan, Sharon Pitteri, Maria Barna
Millions of ribosomes are packed within mammalian cells, yet we lack tools to visualize them in toto and characterize their subcellular composition. In this study, we present ribosome expansion microscopy (RiboExM) to visualize individual ribosomes and an optogenetic proximity-labeling technique (ALIBi) to probe their composition. We generated a super-resolution ribosomal map, revealing subcellular translational hotspots and enrichment of 60S subunits near polysomes at the endoplasmic reticulum (ER). We found that Lsg1 tethers 60S to the ER and regulates translation of select proteins. Additionally, we discovered ribosome heterogeneity at mitochondria guiding translation of metabolism-related transcripts. Lastly, we visualized ribosomes in neurons, revealing a dynamic switch between monosomes and polysomes in neuronal translation. Together, these approaches enable exploration of ribosomal localization and composition at unprecedented resolution.
arXiv
Understanding entropy production via a thermal zero-player game
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-07 20:00 EST
A new thermal bath scheme for Ising-Conway Entropy Game (ICEg) is introduced. New game moves in sampling the given temperature is achieved via Monte Carlo dynamics of both Metropolis and Glauber as a stochastic game. This kind of approach makes the game an ideal tool for demonstrating thermal dependency of entropy production in a novel way. Using this new approach, Ising-Conway Entropy game’s rate of entropy production depending on different temperatures are explored. Thermalized game is shown to be physically interesting and plausible test bed for studying complex dynamical systems in classical statistical mechanics, that is conceptually simple, pedagogically accessible, yet realistic.
Statistical Mechanics (cond-mat.stat-mech)
4 pages, 7 figures
Anomalous Thickness Dependence of the Vortex Pearl Length in Few-Layer NbSe2
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-07 20:00 EST
Nofar Fridman, Tomer Daniel Feld, Avia Noah, Ayelet Zalic, Maya Markman, T.R Devidas, Yishay Zur, Einav Grynszpan, Alon Gutfreund, Itay Keren, Atzmon Vakahi, Sergei Remennik, Kenji Watanabe, Takashi Taniguchi, Martin Emile Huber, Igor Aleiner, Hadar Steinberg, Oded Agam, Yonathan Anahory
The coexistence of multiple types of orders is a common thread in condensed matter physics and unconventional superconductors. The nature of superconducting orders may be unveiled by analyzing local perturbations such as vortices. For thin films, the vortex magnetic profile is characterized by the Pearl-length {\Lambda}, which is inversely proportional to the 2D superfluid density; hence, normally, also inversely proportional to the film thickness, d. Here we employ the scanning SQUID-on-tip microscopy to measure {\Lambda} in NbSe2 flakes with thicknesses ranging from N=3 to 53 layers. For N>10, we find the expected dependence {\Lambda}{\varpropto}1/d. However, six-layer films show a sharp increase of {\Lambda} deviating by a factor of three from the expected value. This value remains fixed for N=3 to 6. This unexpected behavior suggests the competition between two orders; one residing only on the first and last layers of the film while the other prevails in all layers.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Main text: 10 pages, 4 figures. Supplementary information: 13 pages, 6 figures
Constrained many-body phases in a $\mathbb{Z}_2$-Higgs lattice gauge theory
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-03-07 20:00 EST
Alexander Schuckert, Stefan Kühn, Kevin C. Smith, Eleanor Crane, Steven M. Girvin
We study the ground-state phase diagram of a one-dimensional $\mathbb{Z}_2$ lattice gauge theory coupled to soft-core bosonic matter at unit filling, inspired by the Higgs sector of the standard model. Through a combination of analytical perturbative approaches, exact diagonalization, and density-matrix-renormalization-group simulations, we uncover a rich phase diagram driven by gauge-field-mediated resonant pair hopping and the confinement of single particles. The pair hopping results in a bunching state with superextensive energy and macroscopic particle number fluctuations at strong electric field strengths and weak on-site interactions. The bunching state crosses over into a pair superfluid phase as the on-site interaction increases, characterized by a finite superfluid density and powerlaw-decaying pair correlations. At large on-site interaction strengths and driven by effective interactions induced by the gauge constraint, the superfluid transitions into an incompressible pair Mott insulator phase. At weak field strengths and on-site interactions, we find a plasma-like region, where single bosons exhibit large short-range correlations and the ground state is composed almost equally of states with even and odd local boson occupation. The presence of a bunching state with large number fluctuations, which is difficult to study using classical numerics, motivates experimental realizations in hybrid boson-qubit quantum simulation platforms such as circuit QED, neutral atoms, and trapped ions. Our findings highlight the rich interplay between gauge fields and soft-core bosonic matter.
Quantum Gases (cond-mat.quant-gas), High Energy Physics - Lattice (hep-lat), High Energy Physics - Phenomenology (hep-ph), Nuclear Theory (nucl-th), Quantum Physics (quant-ph)
4+2 pages, 5+1 figures
Emergent active turbulence and intermittency in dense algal suspensions of Chlamydomonas reinhardtii
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-07 20:00 EST
Prince Vibek Baruah, Nadia Bihari Padhan, Biswajit Maji, Rahul Pandit, Prerna Sharma
Active-fluid turbulence has been found in bacterial suspensions, but not so far in their algal counterparts. We present the first experimental evidence for turbulence in dense algal suspensions of Chlamydomonas reinhardtii. We carry out a detailed analysis of the statistical properties of the flow present in these cell suspensions and show that they are quantitatively distinct from their counterparts in two-dimensional fluid and bacterial turbulence. Both kinetic-energy and density spectra of the fluid flow in algal turbulence show power-law regimes with unique scaling exponents. The fluid velocity probability distribution function (PDF) is strongly non-Gaussian and the length dependence of the PDF of fluid-velocity increments indicates small-scale intermittency. We compare and contrast our results with recent theoretical predictions for active-scalar turbulence and active glasses. Overall, our results highlight that active turbulence can arise, even in absence of orientational instabilities, so it is not limited to bacterial suspensions but it can also be found in many biological systems with free-swimming micro-organisms.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech), Chaotic Dynamics (nlin.CD)
9 pages (main article), 5 figures (main article), 3 pages (supplementary information), 3 figures (supplementary information)
Materials Graph Library (MatGL), an open-source graph deep learning library for materials science and chemistry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Tsz Wai Ko, Bowen Deng, Marcel Nassar, Luis Barroso-Luque, Runze Liu, Ji Qi, Elliott Liu, Gerbrand Ceder, Santiago Miret, Shyue Ping Ong
Graph deep learning models, which incorporate a natural inductive bias for a collection of atoms, are of immense interest in materials science and chemistry. Here, we introduce the Materials Graph Library (MatGL), an open-source graph deep learning library for materials science and chemistry. Built on top of the popular Deep Graph Library (DGL) and Python Materials Genomics (Pymatgen) packages, our intention is for MatGL to be an extensible batteries-included'' library for the development of advanced graph deep learning models for materials property predictions and interatomic potentials. At present, MatGL has efficient implementations for both invariant and equivariant graph deep learning models, including the Materials 3-body Graph Network (M3GNet), MatErials Graph Network (MEGNet), Crystal Hamiltonian Graph Network (CHGNet), TensorNet and SO3Net architectures. MatGL also includes a variety of pre-trained universal interatomic potentials (aka foundational materials models (FMM)’’) and property prediction models are also included for out-of-box usage, benchmarking and fine-tuning. Finally, MatGL includes support for Pytorch Lightning for rapid training of models.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
50 pages, 13 figures including Manuscript and Supplementary Inoformation
Intervalley-Coupled Twisted Bilayer Graphene from Substrate Commensuration
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Bo-Ting Chen, Michael G. Scheer, Biao Lian
We show that intervalley coupling can be induced in twisted bilayer graphene (TBG) by aligning the bottom graphene layer with either of two types of commensurate insulating triangular Bravais lattice substrate. The intervalley coupling folds the $\pm K$ valleys of TBG to $\Gamma$-point and hybridizes the original TBG flat bands into a four-band model equivalent to the $p_x$-$p_y$ orbital honeycomb lattice model, in which the second conduction and valence bands have quadratic band touchings and can become flat due to geometric frustration. The spin-orbit coupling from the substrate opens gaps between the bands, yielding topological bands with spin Chern numbers $\mathcal{C}$ up to $\pm 4$. For realistic substrate potential strengths, the minimal bandwidths of the hybridized flat bands are still achieved around the TBG magic angle $\theta_M=1.05^\circ$, and their quantum metrics are nearly ideal. We identify two candidate substrate materials Sb$_2$Te$_3$ and GeSb$_2$Te$_4$, which nearly perfectly realize the commensurate lattice constant ratio of $\sqrt{3}$ with graphene. These systems provide a promising platform for exploring strongly correlated topological states driven by geometric frustration.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Effect of Alloying on Intrinsic Ductility in WTaCrV High Entropy Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Akshay Korpe, Osman El-Atwani, Enrique Martinez Saez
Tungsten (W) exhibits desirable properties for extreme applications, such as the divertor in magnetic fusion reactors, but its practicality remains limited due to poor formability and insufficient irradiation resistance. In this work, we study the intrinsic ductility of body-centered cubic WTaCrV based high entropy alloys (HEAs), which are known to exhibit excellent irradiation resistance. The ductility evaluations are carried out using a criterion based on the competition between the critical stress intensity factors for emission (KIe) and cleavage (KIc) in the {110} slip planes and {110} crack planes, which are evaluated within the linear elastic fracture mechanics framework and computed using density functional theory calculations. The results suggest that increasing the alloying concentrations of V and reducing the concentrations of W can significantly improve the ductility in these HEAs. The elastic anisotropy for these HEAs is analyzed using the Zener anisotropy ratio and its correlation with the concentration of W in the alloys is studied. Results indicate that these alloys tend to be fairly isotropic independently from the concentration of W in them. The computed data for the elastic constants of these HEAs is also compared against the available experimental data. The results are in good agreement, hence validating the robustness and accuracy of the computational methods. Multiple phenomenological ductility metrics were also computed and analyzed against the analytical model. The results suggest that these models may have higher computational efficiency due to less number of parameters required for their computation. Some models, like the surrogate D parameter and the Pugh ratio, show a good correlation with the Rice model. The potential of these empirical models to serve as surrogate screening models for optimizing the compositional space is also discussed.
Materials Science (cond-mat.mtrl-sci)
Magnetotransport Properties in Epitaxial Films of Metallic Delafossite PdCoO$_2$: Effects of Thickness and Width Variations in Hall Bar Devices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Arnaud P. Nono Tchiomo, Anand Sharma, Sethulakshmi Sajeev, Anna Scheid, Peter A. van Aken, Takayuki Harada, Prosper Ngabonziza
We report on a combined structural and magnetotransport study of Hall bar devices of various lateral dimensions patterned side-by-side on epitaxial PdCoO$_2$ thin films. We study the effects of both the thickness of the PdCoO$_2$ film and the width of the channel on the electronic transport and the magnetoresistance properties of the Hall bar devices. All the films with thicknesses down to 4.88 nm are epitaxially oriented, phase pure, and exhibit a metallic behavior. At room temperature, the Hall bar device with the channel width $\text{W}=2.5, \mu\text{m}$ exhibits a record resistivity value of $0.85,\mu\Omega$cm, while the value of $2.70,\mu\Omega$cm is obtained in a wider device with channel width $\text{W}=10, \mu\text{m}$. For the 4.88 nm thick sample, we find that while the density of the conduction electrons is comparable in both channels, the electrons move about twice as fast in the narrower channel. At low temperatures, for Hall bar devices of channel width $2.5,\mu\text{m}$ fabricated on epitaxial films of thicknesses 4.88 and 5.21 nm, the electron mobilities of $\approx$ 65 and 40 cm$^2$V$^{-1}$s$^{-1}$, respectively, are extracted. For thin-film Hall bar devices of width $10,\mu\text{m}$ fabricated on the same 4.88 and 5.21 nm thick samples, the mobility values of $\approx$ 32 and 18 cm$^2$V$^{-1}$s$^{-1}$ are obtained. The magnetoresistance characteristics of these PdCoO$_2$ films are observed to be temperature dependent and exhibit a dependency with the orientation of the applied magnetic field. When the applied field is oriented 90° away from the crystal $c$-axis, a persistent negative MR at all temperatures is observed; whereas when the field is parallel to the $c$-axis, the negative magnetoresistance is suppressed at temperatures above 150K.
Materials Science (cond-mat.mtrl-sci)
5 figures in Maintext and 8 figures in supplementary
Mapping strain and structural heterogeneities around bubbles in amorphous ionically conductive Bi$_2$O$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Ellis Rae Kennedy, Stephanie M. Ribet, Ian S. Winter, Caitlin A. Kohnert, Yongqiang Wang, Karen C. Bustillo, Colin Ophus, Benjamin K. Derby
While amorphous materials are often approximated to have a statistically homogeneous atomic structure, they frequently exhibit localized structural heterogeneity that challenges simplified models. This study uses 4D scanning transmission electron microscopy to investigate the strain and structural modifications around gas bubbles in amorphous Bi$_2$O$_3$ induced by argon irradiation. We present a method for determining strain fields surrounding bubbles that can be used to measure the internal pressure of the gas. Compressive strain is observed around the cavities, with higher-order crystalline symmetries emerging near the cavity interfaces, suggesting paracrystalline ordering as a result of bubble coarsening. This ordering, along with a compressive strain gradient, indicates that gas bubbles induce significant localized changes in atomic packing. By analyzing strain fields with maximum compressive strains of 3%, we estimate a lower bound on the internal pressure of the bubbles at 2.5 GPa. These findings provide insight into the complex structural behavior of amorphous materials under stress, particularly in systems with gas inclusions, and offer new methods for probing the local atomic structure in disordered materials. Although considering structural heterogeneity in amorphous systems is non-trivial, these features have crucial impacts on material functionalities, such as mechanical strength, ionic conductivity, and electronic mobility.
Materials Science (cond-mat.mtrl-sci)
13 pages, 7 figures. E.R. Kennedy and S.M. Ribet contributed equally to this work
A universal scaling of condensation temperature in quantum fluids
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-07 20:00 EST
The phenomena of superconductivity and superfluidity are believed to originate from the same underlying physics, namely the condensation of either bosons or pairs of fermions (Cooper pairs). In this work I complied and analyzed literature data for a number of quantum fluids and showed that indeed they all follow the same simple scaling law. The critical temperature for condensation T$_c$ is found to scale with the condensate coherence length $\xi$ and the effective mass of condensing particles m$^{\ast}$. The scaling plot includes members of most known classes of superconductors, as well as a number of superfluids and condensates, such as $^3$He, $^4$He, dilute Bose and Fermi gases, excitons, polaritons, neutron superfluid and proton superconductor in neutron stars, nuclear pairing, quark–antiquark condensate and Higgs condensate. The scaling plot spans more that 24 orders of magnitude of critical temperatures, albeit the scaling exponent is not the one predicted by theory. The plot might help the search for a dark matter particle.
Superconductivity (cond-mat.supr-con), Quantum Gases (cond-mat.quant-gas), General Relativity and Quantum Cosmology (gr-qc), High Energy Physics - Phenomenology (hep-ph)
Classification of Fragile Topology Enabled by Matrix Homotopy
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Ki Young Lee, Stephan Wong, Sachin Vaidya, Terry A. Loring, Alexander Cerjan
The moire flat bands in twisted bilayer graphene have attracted considerable attention not only because of the emergence of correlated phases but also due to their nontrivial topology. Specifically, they exhibit a new class of topology that can be nullified by the addition of trivial bands, termed fragile topology, which suggests the need for an expansion of existing classification schemes. Here, we develop a Z2 energy-resolved topological marker for classifying fragile phases using a system’s position-space description, enabling the direct classification of finite, disordered, and aperiodic materials. By translating the physical symmetries protecting the system’s fragile topological phase into matrix symmetries of the system’s Hamiltonian and position operators, we use matrix homotopy to construct our topological marker while simultaneously yielding a quantitative measure of topological robustness. We show our framework’s effectiveness using a C2T-symmetric twisted bilayer graphene model and photonic crystal as a continuum example. We have found that fragile topology can persist both under strong disorder and in heterostructures lacking a bulk spectral gap, and even an example of disorder-induced re-entrant topology. Overall, the proposed scheme serves as an effective tool for elucidating aspects of fragile topology, offering guidance for potential applications across a variety of experimental platforms from topological photonics to correlated phases in materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph), Optics (physics.optics)
18 pages, 11 figures
Enhanced superconducting correlations in the Emery model and its connections to strange metallic transport and normal state coherence
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
Sijia Zhao, Rong Zhang, Wen O. Wang, Jixun K. Ding, Tianyi Liu, Brian Moritz, Edwin W. Huang, Thomas P. Devereaux
Numerical evidence for superconductivity in the single-band Hubbard model is elusive or ambiguous despite extensive study, raising the question of whether the single-band Hubbard model is a faithful low energy effective model for cuprates, and whether explicitly including the oxygen ions will recover the properties necessary for superconducting transition. Here we show, by using numerically exact determinant quantum Monte Carlo (DQMC) simulations of the doped two-dimensional three-band Emery model, that while the single-band model exhibits strikingly T-linear transport behavior, the three-band model shows a low temperature resistivity curvature indicating a crossover to a more metallic transport regime. Evidence has also been found in thermodynamic and superconducting measurements, which suggests that some degree of coherence in transport might be necessary for the high-temperature superconductivity in cuprates, further implying a possible connection between superconducting and transport behaviors.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
5 pages, 3 figures (main text)
Resistive Anomaly near a Ferromagnetic Phase Transition: A Classical Memory Effect
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
Dmitrii L. Maslov, Vladimir I. Yudson, Cristian D. Batista
We investigate resistive anomalies in metals near ferromagnetic phase transitions, focusing on the role of long-range critical fluctuations. Our analysis reveals that diffusive motion of electrons near the critical temperature ($T_c$) enhances a singular behavior of the resistivity near $T_c$ through a classical memory effect, surpassing the prediction by Fisher and Langer \cite{Fisher:1968}. We show that, close enough to $T_c$, the resistivity exhibits a cusp or anticusp, whose profile is controlled by the critical exponent of the order parameter. We also parameterize the non-Drude behavior of the optical conductivity due to a classical memory effect in terms of critical exponents. These findings offer a deeper understanding of resistive anomalies and their connection to critical exponents in metallic systems.
Strongly Correlated Electrons (cond-mat.str-el)
7 pages, 2 figures
Machine learning driven search of hydrogen storage materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Tanumoy Banerjee, Kevin Ji, Weiyi Xia, Gaoyuan Ouyang, Tyler Del Rose, Ihor Z. Hlova, Benjamin Ueland, Duane D. Johnson, Cai-Zhuan Wang, Ganesh Balasubramanian, Prashant Singh
The transition to a low-carbon economy demands efficient and sustainable energy-storage solutions, with hydrogen emerging as a promising clean-energy carrier and with metal hydrides recognized for their hydrogen-storage capacity. Here, we leverage machine learning (ML) to predict hydrogen-to-metal (H/M) ratios and solution energy by incorporating thermodynamic parameters and local lattice distortion (LLD) as key features. Our best-performing ML model provides improvements to H/M ratios and solution energies over a broad class of ternary alloys (easily extendable to multi-principal-element alloys), such as Ti-Nb-X (X = Mo, Cr, Hf, Ta, V, Zr) and Co-Ni-X (X = Al, Mg, V). Ti-Nb-Mo alloys reveal compositional effects in H-storage behavior, in particular Ti, Nb, and V enhance H-storage capacity, while Mo reduces H/M and hydrogen weight percent by 40-50%. We attributed to slow hydrogen kinetics in molybdenum rich alloys, which is validated by our pressure-composition isotherm (PCT) experiments on pure Ti and Ti5Mo95 alloys. Density functional theory (DFT) and molecular simulations also confirm that Ti and Nb promote H diffusion, whereas Mo hinders it, highlighting the interplay between electronic structure, lattice distortions, and hydrogen uptake. Notably, our Gradient Boosting Regression model identifies LLD as a critical factor in H/M predictions. To aid material selection, we present two periodic tables illustrating elemental effects on (a) H2 wt% and (b) solution energy, derived from ML, and provide a reference for identifying alloying elements that enhance hydrogen solubility and storage.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
34 pages, 12 figures, 87 references
Stress-stress correlations in two-dimensional amorphous and crystalline solids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-07 20:00 EST
Jimin Bai, Long-Zhou Huang, Jin Shang, Yun-Jiang Wang, Jie Zhang, Matteo Baggioli
Stress-stress correlations in crystalline solids with long-range order can be straightforwardly derived using elasticity theory. In contrast, the `emergent elasticity’ of amorphous solids, rigid materials characterized by an underlying disordered structure, defies direct explanation within traditional theoretical frameworks. To address this challenge, tensor gauge theories have been recently proposed as a promising approach to describe the emergent elasticity of disordered solids and predict their stress-stress correlations. In this work, we revisit this problem in two-dimensional amorphous and crystalline solids by employing a canonical elasticity theory approach, supported by experimental and simulation data. We demonstrate that, with respect to static stress-stress correlations, the response of a 2D disordered solid is indistinguishable from that of a 2D isotropic crystalline solid and it is well predicted by vanilla elasticity theory. Moreover, we show that the presence of pinch-point singularities in the stress response is not an exclusive feature of amorphous solids. Our results confirm previous observations about the universal character of static stress-stress correlations in crystalline and amorphous packings.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
v1: comments welcome
Principal component analysis for 5/2 fractional quantum Hall states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Zhe Zhang, Jiajie Qiao, Xiaoliang Wu, Shaowen Yu, Qin Jin
For the special single-layer fractional quantum Hall system with a filling factor of 5/2, which has an even denominator, this paper uses principal component analysis (PCA) to study its behavior under the breaking of particle-hole symmetry. By introducing a model three-body potential to represent the mechanism of particle-hole symmetry breaking, the paper finds that the 5/2 system evolves into two types of special topological quantum states with non-Abelian statistics as the strength and direction of the three-body potential vary. The transition points of these states correspond to the particle-hole symmetric pure Coulomb interaction system. Our results validate the applicability of machine learning as a new research tool in fractional quantum Hall systems. Furthermore, machine learning directly analyzes the raw wave functions, without relying on prior empirical theoretical assumptions and models, making it applicable to a broader range of fractional quantum Hall systems experiencing phase transitions due to particle-hole symmetry breaking.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas)
Unveiling the Oxidation Mechanisms of Octa-Penta Graphene: A Multidimensional Exploration from First-Principles to Machine Learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Chenyi Zhou, Rubin Huo, Boyi Situ, Zihan Yan, Zhe Zhang, Yusong Tu
Octa-penta graphene (OPG), a novel carbon allotrope characterized by its distinctive arrangement of pentagonal and octagonal rings, has garnered considerable attention due to its exceptional structure and functional properties. This study systematically investigates the oxidation mechanisms of OPG and elucidates the oxygen migration patterns on the OPG monolayer through first-principles calculations and machine-learning-based molecular dynamics (MLMD) simulations. Specifically, the oxidation processes on OPG-L and OPG-Z involve exothermic chemisorption, where oxygen molecules dissociate at the surfaces, forming stable epoxy groups. Furthermore, the integrated-crystal orbital Hamilton population (ICOHP) and Bader charge analyses provide insights into the physical mechanisms of oxygen atom adsorption. Importantly, we found that oxidation also impact the electronic properties of OPG, with OPG-L retaining its metallic characteristics post-oxygen adsorption, whereas OPG-Z undergoes a transformation from a metallic to a semiconducting state due to the introduction of oxygen. Oxygen migration on OPG monolayer involves breaking and reforming of C-O bonds, with varying stability across adsorption sites and limited migration along the basal plane. MLMD simulations corroborate these migration patterns, offering detailed migration trajectories consistent with theoretical predictions. These findings enhance the understanding of oxygen migration dynamics on OPG, facilitate its experimental validations, and highlight its potential as a novel 2D material for applications in batteries, heat-resistant materials, and oxidation-resistant coatings.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
A Foundational Potential Energy Surface Dataset for Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Aaron D. Kaplan (1), Runze Liu (2), Ji Qi (2), Tsz Wai Ko (2), Bowen Deng (1 and 3), Janosh Riebesell (1 and 4), Gerbrand Ceder (1), Kristin A. Persson (1 and 3), Shyue Ping Ong (2) ((1) Lawrence Berkeley National Laboratory, (2) University of California San Diego, (3) University of California Berkeley, (4) University of Cambridge)
Accurate potential energy surface (PES) descriptions are essential for atomistic simulations of materials. Universal machine learning interatomic potentials (UMLIPs)$^{1-3}$ offer a computationally efficient alternative to density functional theory (DFT)$^4$ for PES modeling across the periodic table. However, their accuracy today is fundamentally constrained due to a reliance on DFT relaxation data.$^{5,6}$ Here, we introduce MatPES, a foundational PES dataset comprising $\sim 400,000$ structures carefully sampled from 281 million molecular dynamics snapshots that span 16 billion atomic environments. We demonstrate that UMLIPs trained on the modestly sized MatPES dataset can rival, or even outperform, prior models trained on much larger datasets across a broad range of equilibrium, near-equilibrium, and molecular dynamics property benchmarks. We also introduce the first high-fidelity PES dataset based on the revised regularized strongly constrained and appropriately normed (r$^2$SCAN) functional$^7$ with greatly improved descriptions of interatomic bonding. The open source MatPES initiative emphasizes the importance of data quality over quantity in materials science and enables broad community-driven advancements toward more reliable, generalizable, and efficient UMLIPs for large-scale materials discovery and design.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
The first three listed authors contributed equally to this work. For training data, see this http URL or this https URL
Spectral signature of periodic modulation and sliding of pseudogap state in moire system
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Yingzhuo Han, Yingbo Wang, Yucheng Xue, Jiefei Shi, Xiaomeng Wang, Kenji Watanabe, Takashi Taniguchi, Jian Kang, Yuhang Jiang, Jinhai Mao
The nature of the pseudogap state is widely believed as a key to understanding the pairing mechanism underlying unconventional superconductivity. Over the past two decades, significant efforts have been devoted to searching for spontaneous symmetry breaking or potential order parameters associated with these pseudogap states, aiming to better characterize their properties. Recently, pseudogap states have also been realized in moire systems with extensive gate tunability, yet their local electronic structure remains largely unexplored8. In this study, we report the observation of gate-tunable spontaneous symmetry breaking and sliding behavior of the pseudogap state in magic-angle twisted bilayer graphene (MAtBG) using spectroscopic imaging scanning tunneling microscopy. Our spectroscopy reveals a distinct pseudogap at 4.4 K within the doping range -3 < v < -2. Spectroscopic imaging highlights a gap size modulation at moire scale that is sensitive to the filling, indicative of a wave-like fluctuating pseudogap feature. Specifically, the positions of gap size minima (GSM) coincide with regions of the highest local density of states (LDOS) at the filling v = -2.63, but a unidirectional sliding behavior of GSM is observed for other fillings. In addition, the pseudogap size distribution at certain doping levels also causes a clear nematic order, or an anisotropic gap distribution. Our results have shed light on the complex nature of this pseudogap state, revealing critical insights into the phase diagram of correlated electron systems.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
The file contains four Figures
$1/f$ noise in the Ising model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-07 20:00 EST
Rahul Chhimpa, Avinash Chand Yadav
We simulate the $N$-spin critical Ising model on a square lattice using Glauber dynamics and consider the typical one-unit time equal to $N$ single-spin-flip attempts. The divergence of correlation time with the linear extent of the system results in critical slowing down, a challenge to equilibration because the spin configurations generated in such a way are temporally correlated. We examine temporal correlations in the number of accepted spin flips and show a signature of non-trivial long-time correlation of a logarithmically decaying form or the corresponding power spectral density follows canonical $1/f$ noise.
Statistical Mechanics (cond-mat.stat-mech)
5 pages, 6 Figures
Chiral currents at zero magnetic field in some two-dimensional superconductors
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
Non-reciprocal critical currents without applying an external magnetic field have been observed recently in several superconductors, in various forms of Graphene, a Kagome compound and in an under-doped cuprate. A necessary requirement for this is that the usual supercurrent be accompanied by a chiral super-current, i.e. with the symmetry of a hall current; equivalently that the superfluid density tensor have a chiral component. It also requires inversion breaking. The conditions for this phenomena are derived to find that their normal states must break time-reversal and chirality and that the superconducting states must in addition be non-unitary. Each of the superconductors where spontaneous non-reciprocal critical currents are observed have shown some evidence for such broken symmetries in the normal state. The superconducting state of such materials have topological edge currents, but their projected electro-magnetic part is in general not an integer. The edge states are protected in the superconductor due to a gap. Under ideal conditions, the normal state should show an anomalous Hall effect.
Strongly Correlated Electrons (cond-mat.str-el)
The JARVIS Infrastructure is All You Need for Materials Design
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Joint Automated Repository for Various Integrated Simulations (JARVIS) is a comprehensive infrastructure offering databases, tools, tutorials, and benchmarks for multiscale, multimodal, forward, and inverse materials design. Emphasizing open access principles and reproducibility, it integrates theoretical and experimental methodologies such as density functional theory, quantum Monte Carlo, tight-binding, classical force fields, and machine-learning approaches-including fingerprinting, graph neural networks, and transformer models. Its experimental data collection spans cryogenics, microscopy, and diffraction, covering materials like metals, semiconductors, insulators, superconductors, carbon capture systems, high-strength compounds, and low-dimensional materials, heterostructures and defects. JARVIS disseminates resources via open datasets, web applications, executable scripts, and peer-reviewed publications, ensuring broad accessibility and reproducibility. Widely adopted worldwide, it has facilitated millions of data and tool downloads. By unifying diverse methods and data under one platform, JARVIS drives both fundamental discoveries and real-world innovations, advancing conventional and data-driven materials design.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Square lattice model with staggered magnetic fluxes: zero Chern number topological states and topological flat bands
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
Li-Xiang Chen, Dong-Hao Guan, Lu Qi, Xiuyun Zhang, Ying Han, Ai-Lei He
Staggered magnetic fluxes (SMF) play a crucial role in achieving Chern insulators (CIs), by which a series of CI models have been established on various lattices. In addition, SMF induced higher-order topological insulator (HOTI) in a lattice model has been reported. In this work, we propose a square lattice model with SMF. We find intracellular SMF can induce zero-Chern-number topological insulator (ZCNTI) at quarter filling which hosts topologically protected edge states characterized by the quantized polarization, in analogy to the topological state in two dimensional Su-Schrieffer-Hegger model. When lattice dimerization and intracellular SMF are introduced, there exists HOTI state at half filling. Furthermore, this model hosts topological flat band (TFB) by considering the next-nearest-neighbor hoppings. Several fractional Chern insulator states are investigated when hard-core bosons are filled into this TFB model.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 9 figures, Accepted by Physical Review B
Spin-lattice relaxation of NV centers in nanodiamonds adsorbed on conducting and non-conducting surfaces
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Izidor Benedičič, Yuri Tanuma, Žiga Gosar, Bastien Anézo, Mariusz Mrózek, Adam Wojciechowski, Denis Arčon
The nitrogen-vacancy (NV) centers in nanodiamonds can be utilized as low-cost, highly versatile quantum sensors for studying surface properties in condensed matter physics through the application of relaxometry protocols. For such applications, a detailed knowledge of the intrinsic relaxation processes of NV centers in nanodiamonds is necessary. Here, we study the spin-lattice relaxation rates of NV ensembles in nanodiamonds with average diameters of 40 nm and 3 $\mu$m between room temperature and $\sim$ 6 K. The NV relaxation curves fit to a stretched-exponential form with a stretching exponent $\alpha \approx 0.7$, implying the large distribution of relaxation times of individual centers within nanodiamonds. We determine the Orbach-like scattering on phonons as the leading relaxation mechanism. Finally, we discuss the viability of nanodiamonds as surface sensors when deposited on a metallic substrate and emphasize the need for well-controlled surface preparation techniques.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 4 figures
Engineering nonequilibrium superconducting phases in a voltage-driven superconductor under an external magnetic field
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-07 20:00 EST
We theoretically investigate nonequilibrium properties of a normal metal-superconductor-normal metal (NSN) junction under an external magnetic field. When a bias voltage is applied between the normal-metal leads, the confined superconductor is driven out of equilibrium, resulting in a nonequilibrium quasiparticle distribution function having a two-step structure. Using the nonequilibrium Green’s function technique, we determine a comprehensive phase diagram of the nonequilibrium superconductor. Our analysis reveals that the interplay between Zeeman-split energy bands and the nonequilibrium distribution function gives rise to a rich phase structure. Notably, we find that superconductivity destroyed by a strong external magnetic field revives by applying the bias voltage. This reentrant phenomenon is shown to originate from four effective “Fermi surfaces” that result from the combination of Zeeman-split energy bands and the two-step structure in the nonequilibrium distribution function. Our results demonstrate the possibility of controlling quantum states of matter through the combined engineering of energy band structures and distribution functions.
Superconductivity (cond-mat.supr-con)
12 pages, 8 figures
Investigations of Metal-Organic structures for applications in Organic Spin Valve devices
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Sonia Kaushik, Manisha Priyadarsini, Avinash G. Khanderao, Dileep Kumar
Organic spintronics has drawn the interest of the science community due to various applications in spin-valve devices. But to date, an efficient room-temperature Organic Spin Valve device has not been experimentally realized due to the complicated spin transport at the metal-organic interfaces. These studies are always challenging due to the complicated spin-polarized charge transfer at the metal-organic interfaces. The present study focuses on a comprehensive understanding of the interfacial properties that are essential for advancing device performance and functionality. The Ferromagnetic metals and half-metallic electrodes such as Co, Co2FeAl, etc., and fullerene (C60) bilayer samples are prepared and studied via different structural and magnetic characterizations. Due to the mechanical softness of C60, deep penetration of ferromagnetic metal atoms is observed inside the C60 film. In-situ MOKE measurements reveal the origin of the 23 Å thick magnetic dead layer at the interface, which is attributed to the diffused ferromagnetic clusters exhibiting superparamagnetic behavior. In contrast to the inorganic substrates, magnetic anisotropy tends to develop at 40 Å thick Co film deposited on C60 which enhances with increasing thickness. The XRD measurements confirm the presence of in-plane compressive strain and texturing along the hcp (002) phase in the Co film. The anomaly observed in the hard axis of magnetization is due to high dispersion in the local magnetic anisotropy. The variation of the magnetic anisotropy axis is observed in the Co2FeAlwedge deposited in the proximity of C60. These findings provide valuable insights into the complex interplay between ferromagnetic materials and organic semiconductors offering potential avenues for tailoring magnetoresistance effects and fundamental understanding of organic spintronic devices.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
22 pages,16 figures
Thermoelectric fluctuations of interfering Majorana bound states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Nonequilibrium states produced by electric and thermal voltages ($V$, $V_T$) provide a straightforward insight into underlying degrees of freedom of composite nanostructures and are of particular interest to probe Majorana bound states. Here we explore fluctuations of thermoelectric currents at finite frequencies $\omega$ in a quantum dot coupled to two interfering Majorana bound states. At small $V$ we find that in the emission spectra the differential thermoelectric quantum noise $\partial S^>/\partial V_T$ shows an antiresonance whereas in the absorption spectra Majorana interference induces an antiresonance-resonance pair. At large $V$ this pair is preserved whereas the emission antiresonance turns into an antiresonance-resonance pair identical to the absorption one making $\partial S^>/\partial V_T$ antisymmetric in the frequency $\omega$. This antisymmetry distinguishes Majorana behavior from the one induced by Andreev bound states and does not break at higher temperatures making it attractive for experiments on Majorana interference via thermoelectric fluctuation response.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
16 pages, 10 figures
Physical Review B 111, 125402 (2025)
Anomalous Hall effect in Dirac semimetal probed by in-plane magnetic field
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Shinichi Nishihaya, Hiroaki Ishizuka, Yuki Deguchi, Ayano Nakamura, Tadashi Yoneda, Hsiang Lee, Markus Kriener, Masaki Uchida
Intrinsic anomalous Hall effect (AHE) formulated by geometric properties of Bloch wavefunctions is a ubiquitous transport phenomenon not limited to magnetic systems but also allowed in non-magnetic ones under an external field breaking time-reversal symmetry. On the other hand, detection of field-induced AHE is practically challenging because the band modulation through the Zeeman and spin-orbit couplings is typically small compared to other contributions as induced by the Lorentz force. Here, we demonstrate on Dirac semimetal Cd$_3$As$_2$ films that the field-induced AHE in non-magnetic systems can be quantitatively probed by applying and rotating the magnetic field within the Hall deflection plane. Measurements on the Cd$_3$As$_2$ (112) plane reveal that AHE emerges as a clear three-fold symmetric component for the in-plane field rotation. This intrinsic response becomes more pronounced in ultralow-electron-density films where significant variations in the geometric properties are expected under the magnetic field. Our findings open new opportunities in the research of Hall responses manifested as orbital magnetization in non-magnetic systems.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 4 figures
Pervasive protonation of perovskite membranes made by the water-soluble sacrificial layer method
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Umair Saeed, Felip Sandiumenge, Kumara Cordero-Edwards, Jessica Padilla-Pantoja, José Manuel Caicedo Roque, David Pesquera, José Santiso, Gustau Catalan
The fabrication of perovskite oxide free-standing films (membranes) by lift-off methods using water-soluble sacrificial layers is appealing because of the new mechanical degrees of freedom that these membranes present over conventional epitaxial films. However, little is known about how their fabrication process, and in particular the exposure to water during the etching step, affects their properties. Here, we investigate how membranes of two perovskite archetypes, antiferroelectric PbZrO3 and paraelectric SrTiO3, are affected by water-based etching step. Using Raman spectroscopy and X-ray diffraction, we find evidence that hydrogen penetrates the perovskite structure. Concomitant with this protonation, the functional properties also change, and both materials display ferroelectric-like behavior that is absent in bulk ceramics or hydrogen-free films at room temperature. We also find that thermal annealing can be used to expel the hydrogen from the membranes, which henceforth recover bulk-like properties. The two main conclusions of this work are that (i) any perovskite membrane made by sacrificial layer hydrolysis is vulnerable to hydrogen penetration (protonation) that can induce important but extrinsic changes in functional properties, and (ii) the hydrogen can, and should, be expelled by annealing to recover intrinsic behaviour.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
21 pages, 5 figures, supplementary file included
Random search with stochastic resetting: when finding the target is not enough
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-07 20:00 EST
In this paper we consider a random search process with stochastic resetting and a partially accessible target $\calU$. That is, when the searcher finds the target by attaching to its surface $\partial \calU$ it does not have immediate access to the resources within the target interior. After a random waiting time, the searcher either gains access to the resources within or detaches and continues its search process. We also assume that the searcher requires an alternating sequence of periods of bulk diffusion interspersed with local surface interactions before being able to attach to the surface. The attachment, detachment and target entry events are the analogs of adsorption, desorption and absorption of a particle by a partially reactive surface in physical chemistry. In applications to animal foraging, the resources could represent food or shelter while resetting corresponds to an animal returning to its home base. We begin by considering a Brownian particle on the half-line with a partially accessible target at the origin $x=0$. We calculate the non-equilibrium stationary state (NESS) in the case of reversible adsorption and obtain the corresponding first passage time (FPT) density for absorption when adsorption is only partially reversible. We then reformulate the stochastic process in terms of a pair of renewal equations that relate the probability density and FPT density for absorption in terms of the corresponding quantities for irreversible adsorption. The renewal equations allow us to incorporate non-Markovian models of absorption and desorption. They also provide a useful decomposition of quantities such as the mean FPT (MFPT) in terms of the number of desorption events and the statistics of the waiting time density. Finally, we consider various extensions of the theory, including higher-dimensional search processes and an encounter-based model of absorption.
Statistical Mechanics (cond-mat.stat-mech), Quantitative Methods (q-bio.QM)
19 pages, 11 figures
Co-existing magnetization reversal mechanisms in shakti spin ice systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Vladyslav M. Kuchkin, Unnar B. Arnalds, Hannes Jónsson, Pavel F. Bessarab
The switching mechanisms in artificial spin ice systems are investigated with focus on shakti and modified shakti lattices. Minimum energy paths are calculated using the geodesic nudged elastic band (GNEB) method implemented with a micromagnetic description of the system, including the internal magnetic structure of the islands and edge modulations. Two switching mechanisms, uniform magnetization rotation and domain wall formation, are found to have comparable activation energy. The preference for one over the other depends strongly on the saturation magnetization and the magnetic ordering of neighboring islands. Surprisingly, these mechanisms can coexist, leading to an enhanced probability of magnetization reversal. These results provide valuable insight that can help control internal magnetization switching processes in spin ice systems and help predict their thermodynamic properties.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 6 figures
Minimizing sensor-sample distances in scanning nitrogen-vacancy magnetometry
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Zhewen Xu, Marius L. Palm, William S. Huxter, Konstantin Herb, John M. Abendroth, Karim Bouzehouane, Olivier Boulle, Mihai S. Gabor, Joseba Urrestarazu Larranaga, Andrea Morales, Jan Rhensius, Gabriel F. Puebla-Hellmann, Christian L. Degen
Scanning magnetometry with nitrogen-vacancy (NV) centers in diamond has led to significant advances in the sensitive imaging of magnetic systems. The spatial resolution of the technique, however, remains limited to tens to hundreds of nanometers, even for probes where NV centers are engineered within 10 nm from the tip apex. Here, we present a correlated investigation of the crucial parameters that determine the spatial resolution: the mechanical and magnetic stand-off distances, as well as the sub-surface NV center depth in diamond. We study their contributions using mechanical approach curves, photoluminescence measurements, magnetometry scans, and nuclear magnetic resonance (NMR) spectroscopy of surface adsorbates. We first show that the stand-off distance is mainly limited by features on the surface of the diamond tip, hindering mechanical access. Next, we demonstrate that frequency-modulated atomic force microscopy (FM-AFM) feedback partially overcomes this issue, leading to closer and more consistent magnetic stand-off distances (26-87 nm) compared to the more common amplitude-modulated (AM-AFM) feedback (43-128 nm). FM operation thus permits improved magnetic imaging of sub-100-nm spin textures, shown for the spin cycloid in BFO and domain walls in a CoFeB synthetic antiferromagnet. Finally, by examining 1H and 19F NMR signals in soft contact with a polytetrafluoroethylene surface, we demonstrate a minimum NV-to-sample distance of 7.9+/-0.4 nm.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Accepted Version. 34 pages, 6 figures. Supporting Information available on request
ACS Nano 19, 8, 8255-8265 (2025)
Hydroxylation-driven surface reconstruction at the origin of compressive-to-tensile stress transition in metal oxide nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Experiments reveal negative (non-Laplacian) surface stresses in metal oxide nanoparticles, partly associated with humidity during fabrication and annealing. Using a neural network interatomic potential for MgO, we prove that water adsorption induces surface hydroxylation, shifting facets from {100} to {110} to {111} and switching the average surface stress from positive to negative. Predicted lattice strains versus nanoparticle size agree well with experiments, clarifying experimental correlations. The new framework informs broad applications in catalysis, sensors, batteries, and biomedicine.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
T-MSD: An improved method for ionic diffusion coefficient calculation from molecular dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Yuxiang Gao, Xiaodong Cao, Zhicheng Zhong
Ionic conductivity is a critical property of solid ionic conductors, directly influencing the performance of energy storage devices such as batteries. However, accurately calculating ionic conductivity or diffusion coefficient remains challenging due to the complex, dynamic nature of ionic motion, which often yield significant deviations, especially at room temperature. In this study, we propose an improved method, T-MSD, to enhance the accuracy and reliability of diffusion coefficient calculations. Combining time-averaged mean square displacement analysis with block jackknife resampling, this method effectively addresses the impact of rare, anomalous diffusion events and provides robust statistical error estimates from a single simulation. Applied to large-scale deep-potential molecular dynamics simulations, we show that T-MSD eliminates the need for multiple independent simulations while ensuring accurate diffusion coefficient calculations across systems of varying sizes and simulation durations. This approach offers a practical and reliable framework for precise ionic conductivity estimation, advancing the study and design of high-performance solid ionic conductors.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Nematic order from phase synchronization of shape oscillations
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-07 20:00 EST
Ioannis Hadjifrangiskou, Sumesh P. Thampi, Rahil N. Valani
We show that a suspension of non-interacting deformable particles subjected to an oscillatory shear flow leads to development of nematic order that arises from the phenomenon of phase synchronization. The synchronized state corresponds to a unique, stable limit cycle confined in the toroidal state space. The limit cycle exists since, unlike rigid particles, deformable particles can modulate aspect ratio, adjust their tumbling rate and thus, achieve phase synchronization. These synchronized regions emerge as Arnold tongues in the parameter-space of the driving amplitude and frequency. Considering the rheological implications of ordering dynamics in soft and active matter, our results motivate oscillatory shear flow experiments with deformable particles.
Soft Condensed Matter (cond-mat.soft)
6 pages, 4 figures
Euler buckling on curved surfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-07 20:00 EST
Euler buckling epitomises mechanical instabilities: An inextensible straight elastic line buckles under compression when the compressive force reaches a critical value $F_\ast>0$. Here, we extend this classical, planar instability to the buckling under compression of an inextensible relaxed elastic line on a curved surface. By weakly nonlinear analysis of an asymptotically short elastic line, we reveal that the buckling bifurcation changes fundamentally: The critical force for the lowest buckling mode is $F_\ast=0$ and higher buckling modes disconnect from the undeformed branch to connect in pairs. Solving the buckling problem numerically, we additionally find a new post-buckling instability: A long elastic line on a curved surface snaps through under sufficient compression. Our results thus set the foundations for understanding the buckling instabilities on curved surfaces that pervade the emergence of shape in biology.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
18 pages, 2 figures
Identifying high-energy electronic states of NV$^-$ centers in diamond
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Minh Tuan Luu, Christopher Linderälv, Zsolt Benedek, Ádám Ganyecz, Gergely Barcza, Viktor Ivády, Ronald Ulbricht
The negatively charged nitrogen-vacancy center in diamond is a prototype photoluminescent point defect spin qubit with promising quantum technology applications, enabled by its efficient optical spin polarization and readout. Its low-lying electronic states and optical spin polarization cycle have been well characterized over decades, establishing it as a benchmark system for state-of-the-art computational methods in point defect research. While the optical cycle is well understood, a comprehensive energetic analysis of higher-lying states has received less attention until recently. In this joint experimental theoretical study, we identify and characterize five high-energy states beyond those involved in the optical cycle. Using transient absorption spectroscopy, we determine their transition energies and relative oscillator strengths. Additionally, we perform two independent numerical studies employing two state-of-the-art post-DFT methods to support the experimental findings and assign energy levels. These results enhance our understanding of the NV center’s energy spectrum and providing a broader reference for benchmarking high-level first-principles methods.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
7 pages, 4 figures, 1 table, and supplementary material
Quantum metric induced magneto-optical effects in $\mathcal{PT}$-symmetric antiferromagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Yongpan Li, Yichen Liu, Cheng-Cheng Liu
The magneto-optical effects (MOEs), as a fundamental physical phenomenon, can reveal the electronic structures of materials. The related probing methods are widely used in the study of magnetic materials. However, space-time inversion ($\mathcal{PT}$) symmetric antiferromagnets were previously believed to be magneto-optically inactive. Here, we point out that this traditional understanding is incorrect. Based on our generic formulas and symmetry analysis, we find that in $\mathcal{PT}$-symmetric antiferromagnets, it is the quantum metric, i.e., the real part of the quantum geometry, that induces MOEs. Combining a tight-binding model and first-principles calculations, we confirm this observation by showing MOEs in the $\mathcal{PT}$-symmetric antiferromagnet. Our work demonstrates that $\mathcal{PT}$-symmetric antiferromagnets previously thought to lack MOEs can indeed exhibit MOEs and greatly broaden the research on MOEs.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph)
Comments are welcome!
Casimir-like effect driven self-assembly of graphene on molten metals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Kristýna Bukvišová, Radek Kalousek, Marek Patočka, Jakub Zlámal, Jakub Planer, Vojtěch Mahel, Daniel Citterberg, Libor Novák, Tomáš Šikola, Suneel Kodambaka, Miroslav Kolíbal
Casimir effect, explained by Hendrik Casimir in 1948, is a macroscopic manifestation of quantum electrodynamics. Symmetry breaking due to space confinement of vacuum fluctuations in between two planar mirrors results in an attractive force acting between the two mirrors. Here, we show that spontaneous self-assembly of two-dimensional (2D) layered materials grown on molten metals (rheotaxy) is driven by the mechanical forces exerted by the liquid on the graphene domain and that these forces are subject to a Casimir-like effect. We present in situ environmental and ultrahigh vacuum scanning electron microscopy observations of chemical vapor deposition of graphene on both solid and molten gold and copper, which reveal that the self-assembly occurs via translational and rotational motions of graphene domains during growth on molten metals. Using high-temperature (~ 1300 K) atomic force microscopy measurements of graphene/molten-metal interfaces, coupled with density functional theory and continuum modelling of 2D layers floating on a liquid surface, we attribute the observed phenomena to Casimir-like effect of surface undulations and give further guidance for achieving seamless stitching of 2D layer domains into large scale monolayers.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
53 pages in total, 3 main figures, 16 supporting figures
Observation of collective charge excitations in a cuprate superconductor
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-07 20:00 EST
Xunyang Hong, Yujie Yan, L. Martinelli, I. Biało, K. von Arx, J. Choi, Y. Sassa, S. Pyon, T. Takayama, H. Takagi, Zhenglu Li, M. Garcia-Fernandez, Ke-Jin Zhou, J. Chang, Qisi Wang
Emergent symmetry breakings in condensed matter systems are often intimately linked to collective excitations. For example, the intertwined spin-charge stripe order in cuprate superconductors is associated with spin and charge excitations. While the collective behavior of spin excitations is well established, the nature of charge excitations remains to be understood. Here we present a high-resolution resonant inelastic x-ray scattering (RIXS) study of charge excitations in the stripe-ordered cuprate La${1.675}$Eu${0.2}$Sr$_{0.125}$CuO$_4$. The RIXS spectra consist of both charge and phonon excitations around the charge ordering wave vector. By modeling the momentum-dependent phonon intensity, the charge-excitation spectral weight is extracted for a wide range of energy. As such, we reveal the highly dispersive nature of the charge excitations, with an energy scale comparable to the spin excitations. Since charge order and superconductivity in cuprates are possibly driven by the same electronic correlations, determining the interaction strength underlying charge order is essential to establishing a comprehensive microscopic model of high-temperature superconductivity.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Supplementary Information available upon request
Emergence of Robust High-Temperature Superconductivity in Li3IrH9 at Moderate Pressures
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-07 20:00 EST
Wendi Zhao, Shumin Guo, Tiancheng Mg, Zhengtao Liu, Chengda Li, Defang Duan, Tian Cui
The discovery of near-room temperature superconductivity in compressed hydrides has sparked intensive efforts to find superconducting hydrides that are stable at low pressure or even ambient pressure. Herein, we present the ternary hydride Li3IrH9 as an exceptional candidate, which exhibits thermodynamic stability above 100 GPa and dynamic stability down to 8 GPa, exhibiting a superconducting transition temperature (Tc) of up to 113 K. In this structure, the broadening and overlapping between the electronic bands of the Ir-H antibonding states and the neighboring H ions result in the intrinsic metallicity of the hydrogen sublattice and drive the emergence of hydrogen-dominated significant electronic states at the Fermi level. Within this specific mechanism, the softened optical modes generated by hydrogen atoms encapsulated in the center of the Li octahedron play a critical role in strengthening electron-phonon coupling, an effect that remains robust even under high-pressures. Through high-throughput computational screening, we further identified a new family of superconductors derived from this prototype, including Li3RhH9 (Tc = 124 K at 20 GPa) and Li3CoH9 (Tc = 80 K at 10 GPa). This work provides original theoretical insights to accelerate the discovery of emerging hydride superconductor families that exhibit robust high-temperature superconductivity under moderate-pressures, along with promising potential for practical implementation.
Superconductivity (cond-mat.supr-con)
15 pages, 5 figures
Capillary jet in a slab of foam
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-07 20:00 EST
Théophile Gaichies, Bryan Giraud, Anniina Salonen, Arnaud Antkowiak, Emmanuelle Rio
A capillary jet plunging into a quasi-2D slab of monodisperse foam of the same solution is studied experimentally. We show that the jet can have a drastic impact on the foam. At small speeds it inflates the channels separating the bubbles. At intermediate speeds, impact with channels creates very small bubbles. At higher speeds, the jet thins the foam films, which can result in bubble rupture. We study the mechanisms behind these processes using an elementary foam formed by three soap films in contact through a Plateau border. We obtain scaling laws, which transfer quantitatively from the elementary foam to the 2D foam.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Unveiling the effect of adding B4C at the W-on-Si interface
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Adele Valpreda (1), Hendrik W. Lokhorst (1), Jacobus M. Sturm (1), Andrey E. Yakshin (1), Marcelo Ackermann (1) ((1) Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, Enschede, Netherlands)
In this study, we investigate the W-on-Si interface and the effect of adding a B4C interlayer at such interface, using low-energy ion scattering (LEIS) spectroscopy, X-ray reflectivity, X-ray diffraction, and transmission electron microscopy with energy dispersive X-ray spectroscopy. We extract the effective width of the interface in three different structures having: no-B4C, 0.24 nm, and 1.2 nm of B4C deposited in between the W and the Si films. The analysis reveals that the W distribution does not get significantly sharper when B4C atoms are deposited at the W-on-Si interface, showing that B4C does not act as a physical barrier against the diffusion of atoms during the deposition of these structures. W/Si thin-film structures are used in various applications, including X-ray optics. While many studies reported that adding a sub-nm thick B4C film at the W/Si interfaces is beneficial for the overall reflectivity of the structures, the physical mechanisms involved were not yet fully understood. In this context, being able to characterize the width of the interfaces with sub-nm resolution is key. In this study, we show how the analysis of the sub-surface signal of the LEIS spectra enables the characterization of the interface W-on-(B4C-)Si, highlighting the importance of systematically extracting the values of the effective interface width for the analysis and understanding of thin-film growth.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Concurrent Multifractality and Anomalous Hall Response in the Nodal Line Semimetal Fe$_3$GeTe$_2$ Near Localization
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
Subramanian Mathimalar, Ambikesh Gupta, Yotam Roet, Stanislaw Galeski, Rafal Wawrzynczak, Mikel Garcia-Diez, Iñigo Robredo, Praveen Vir, Nitesh Kumar, Walter Schnelle, Karin von Arx, Julia Küspert, Qisi Wang, Johan Chang, Yasmine Sassa, Ady Stern, Felix von Oppen, Maia G. Vergniory, Claudia Felser, Johannes Gooth, Nurit Avraham, Haim Beidenkopf
Topological states of matter exhibit unique protection against scattering by disorder. Different topological classes exhibit distinct forms and degrees of protection. Here, we investigate the response of the ferromagnetic nodal line semimetal Fe$_3$GeTe$_2$ to disorder and electronic interactions. By combining global magneto-transport with atomic-scale scanning tunneling spectroscopy we find a simultaneous onset of diverse phenomena below a common temperature scale of about 15 K: A crossover from metallic to insulating temperature dependence of the longitudinal resistivity, saturation of the anomalous Hall conductivity to its maximal value, formation of a sharp zero-bias dip in the tunneling density of state, and emergence of multi-fractal structure of the electronic wavefunction peaking at the Fermi energy. These concurrent observations reflect the emergence of a novel energy scale possibly related to the opening of a gap in the nodal line band of Fe$_3$GeTe$_2$. Our study provides overarching insight into the role of disorder, electronic interactions and Berry curvature in setting the micro- and macro-scale responses of topological semimetals.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Self-consistent tensor network method for correlated super-moiré matter beyond one billion sites
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
Yitao Sun, Marcel Niedermeier, Tiago V. C. Antão, Adolfo O. Fumega, Jose L. Lado
Moiré and super-moiré materials provide exceptional platforms to engineer exotic correlated quantum matter. The vast number of sites required to model moiré systems in real space remains a formidable challenge due to the immense computational resources required. Super-moiré materials push this requirement to the limit, where millions or even billions of sites need to be considered, a requirement beyond the capabilities of conventional methods for interacting systems. Here, we establish a methodology that allows solving correlated states in systems reaching a billion sites, that exploits tensor-network representations of real-space Hamiltonians and self-consistent real-space mean-field equations. Our method combines a tensor-network kernel polynomial method with quantics tensor cross interpolation algorithm, enabling us to solve exponentially large models, including those whose single particle Hamiltonian is too large to be stored explicitly. We demonstrate our methodology with super-moiré systems featuring spatially modulated hoppings, many-body interactions and domain walls, showing that it allows access to self-consistent symmetry broken states and spectral functions of real-space models reaching a billion sites. Our methodology provides a strategy to solve exceptionally large interacting problems, providing a widely applicable strategy to compute correlated super-moiré quantum matter.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)
7 pages, 4 figures
Duality of Wave Modulation and Nanotwinning in Ni-Mn-Ga Martensite via Long-Period Commensurate States
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
P. Veřtát, M. Zelený, A. Sozinov, M. Klicpera, O. Fabelo, R. Chulist, M. Vinogradova, P. Sedlák, H. Seiner, O. Heczko, L. Straka
Understanding the crystal structure of magnetic shape memory alloys is crucial for elucidating their martensite twin boundary supermobility and related functionalities. This study analyzes and discusses the structure of martensitic single crystals of Ni50.0Mn27.7Ga22.3 and Ni50.0Mn28.1Ga21.9. Neutron and X-ray diffraction reveal an anharmonic, incommensurate five-layer modulation that evolves with temperature. This evolution gives rise to two key microstructural features: i) periodic nanodomains, identified as emerging a/b-nanotwins, and ii) long-period commensurate structures, such as the 34O, 24O, and 14O states, whose orthorhombic unit cells inherently realize a/b-nanotwins. Ab initio calculations show that these long-period structures are energetically favorable, leading to a lock-in transition. In the alloys studied, the 24O state is the locked-in phase at low temperatures, whereas literature data indicate that Ni50Mn25Ga25 (exact Ni2MnGa stoichiometry) evolves toward the 14O phase. Crucially, these results unify two seemingly contrasting structural descriptions – wave-like modulation and discrete nanotwinning – thereby establishing a foundation for a deeper understanding of the crystal-structure-functionality relationship in magnetic shape memory alloys.
Materials Science (cond-mat.mtrl-sci)
34 pages, 9 figures at the end, one table at the end
Energy barriers for small electron polaron hopping in bismuth ferrite from first principles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Evidence from first-principles calculations indicates that excess electrons in BiFeO3 form small polarons with energy levels deep inside the electronic band gap. Hence, n-type electronic transport could occur by hopping of small electron polarons rather than by band-like transport. Here, by means of first-principles calculations, small electron polaron hopping in BiFeO3 is investigated. Both bulk BiFeO3 and a typical ferroelectric domain wall, the neutral 71° domain wall, are considered. The latter is included to account for experimental observations of electrical conductivity at domain walls in otherwise insulating ferroelectrics. The object of this study is to shed light on the intrinsic electron conduction in rhombohedral BiFeO3 and the effect of pristine neutral ferroelectric domain walls. The computed energy barriers for small electron polaron hopping are of the order of the thermal energy at room temperature, both in bulk and within the neutral 71° domain wall. The domain wall is found to act as a two-dimensional trap for small electron polarons with a trap depth of about two to three times the thermal energy at room temperature. Based on these findings, the intrinsic n-type mobility and diffusion constant in BiFeO3 at room temperature are estimated, and experimental conductivity data for BiFeO3 are discussed.
Materials Science (cond-mat.mtrl-sci)
Identical Suppression of Spin and Charge Density Wave Transitions in La$_4$Ni$3$O${10}$ by Pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-07 20:00 EST
Rustem Khasanov, Thomas J. Hicken, Igor Plokhikh, Vahid Sazgari, Lukas Keller, Vladimir Pomjakushin, Marek Bartkowiak, Szymon Królak, Michał J. Winiarski, Jonas A. Krieger, Hubertus Luetkens, Tomasz Klimczuk, Dariusz J. Gawryluk, Zurab Guguchia
Understanding the interplay between magnetism and superconductivity in nickelate systems is a key focus of condensed matter research. Microscopic insights into magnetism, which emerges near superconductivity, require a synergistic approach that combines complementary techniques with controlled parameter tuning. In this paper, we present a systematic investigation of the three-layer Ruddlesden-Popper (RP) nickelate La$4$Ni$3$O${10}$ using muon-spin rotation/relaxation ($\mu$SR), neutron powder diffraction (NPD), resistivity, and specific heat measurements. At ambient pressure, two incommensurate spin density wave (SDW) transitions were identified at $T{\rm SDW} \simeq 132$ K and $T^\ast \simeq 90$ K. NPD experiments revealed that the magnetic wave vector $(0, 0.574, 0)$ remains unchanged below 130 K, indicating that the transition at $T^\ast$ corresponds to a reorientation of the Ni magnetic moments within a similar magnetic structure. Comparison of the observed internal magnetic fields with dipole-field calculations reveals a magnetic structure consistent with an antiferromagnetically coupled SDW on the outer two Ni layers, with smaller moments on the inner Ni layer. The internal fields at muon stopping sites appeared abruptly at $T_{\rm SDW}$, suggesting a first-order-like nature of the SDW transition, which is closely linked to the charge density wave (CDW) order occurring at the same temperature ($T_{\rm SDW} = T_{\rm CDW}$). Under applied pressure, all transition temperatures, including $T_{\rm SDW}$, $T^\ast$, and $T_{\rm CDW}$, were suppressed at a nearly uniform rate of $\simeq -13$ K/GPa. This behavior contrasts with the double-layer RP nickelate La$_3$Ni$_2$O$_7$, where pressure enhances the separation of the density wave transitions.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 7 figures
Nuclear magnetic resonance spectroscopy in pulsed magnetic fields
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
This article provides an introduction to nuclear magnetic resonance spectroscopy in pulsed magnetic fields (PFNMR), focusing on its capabilities, applications, and future developments in research involving high magnetic fields. It highlights the significance of PFNMR in enhancing the understanding of solid-state materials, with particular emphasis on those exhibiting complex interactions and strong electronic correlations. Several technical aspects are discussed, including the challenges associated with high-frequency NMR experiments. The power of PFNMR is showcased through several examples, including studies on the topical materials LiCuVO$_4$, SrCu$_2$(BO$_3$)$_2$, and CeIn$_3$, offering insights into their magnetic and electronic properties at high magnetic fields. The article also discusses possible future directions for the technique, including improvements in PFNMR instrumentation and the exploration of materials under extreme conditions. This exposition underscores the role of PFNMR in advancing the frontiers of materials-science research.
Strongly Correlated Electrons (cond-mat.str-el)
21 pages, 19 figures
Contemp. Phys. 65, 40 (2024)
Observation of non-adiabatic Landau-Zener tunneling among Floquet states
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Yun Yen, Marcel Reutzel, Andi Li, Zehua Wang, Hrvoje Petek, Michael Schüler
Electromagnetic fields not only induce electronic transitions but also fundamentally modify the quantum states of matter through strong light-matter interactions. As one established route, Floquet engineering provides a powerful framework to dress electronic states with time-periodic fields, giving rise to quasi-stationary Floquet states. With increasing field strength, non-perturbative responses of the dressed states emerge, yet their nonlinear dynamics remain challenging to interpret. In this work we explore the emergence of non-adiabatic Landau-Zener transitions among Floquet states in Cu(111) under intense optical fields. At increasing field strength, we observe a transition from perturbative dressing to a regime where Floquet states undergo non-adiabatic tunneling, revealing a breakdown of adiabatic Floquet evolution. These insights are obtained through interferometrically time-resolved multi-photon photoemission spectroscopy, which serves as a sensitive probe of transient Floquet state dynamics. Numerical simulations and the theory of instantaneous Floquet states allow us to directly examine real-time excitation pathways in this non-perturbative photoemission regime. Our results establish a direct connection the onset of light-dressing of matter, non-perturbative ultrafast lightwave electronics, and high-optical-harmonic generation in the solids.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics), Quantum Physics (quant-ph)
Relationship between the shear moduli and defect-induced structural relaxation ofhigh-entropy metallic glasses
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-03-07 20:00 EST
Andrey Makarov, Evgenia Gonchrova, Jichao Qiao, Roman Konchakov, Vitaly Khonik
We performed high-frequency shear modulus and calorimetry measurements on seven high-entropy metallic glasses (HEMGs) in the initial, relaxed and crystalline states. It is shown that the shear modulus of HEMGs is intrinsically related with the concentration of defects responsible for structural relaxation. In the absence of structural relaxation, temperature coefficient of shear modulus of glass equals to that of the maternal crystal. All found regularities are governed by a single equation.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
3 Figures
On the nature of the glass transition in metallic glasses after deep relaxation
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-03-07 20:00 EST
A.S. Makarov, G.V. Afonin, R.A. Konchakov, J.C. Qiao, N.P. Kobelev, V.A. Khonik
We performed parallel study of calorimetric and high-frequency shear modulus behavior of Zr-based metallic glasses after deep relaxation just below the glass transition. It is shown that deep relaxation results in the appearance of a strong peak of the excess heat capacity while the shear modulus is moderately affected. A theory assuming high-frequency shear modulus to be a major physical parameter controlling glass relaxation is suggested. The energy barrier for these rearrangements is proportional to the shear modulus while its magnitude, in turn, varies due to the changes in the defect concentration (diaelastic effect). Both dependences lead to the occurrence of heat effects. The excess heat capacity calculated using experimental shear modulus data demonstrates very good agreement with the experimental calorimetric data for all states of glasses. It is argued that the glass transition behavior after deep relaxation of glass is close to a phase transition of the first kind.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
8 Figures
Beyond Disorder: Unveiling Cooperativeness in Multidirectional Associative Memories
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-03-07 20:00 EST
Andrea Alessandrelli, Adriano Barra, Andrea Ladiana, Andrea Lepre, Federico Ricci-Tersenghi
By leveraging tools from the statistical mechanics of complex systems, in these short notes we extend the architecture of a neural network for hetero-associative memory (called three-directional associative memories, TAM) to explore supervised and unsupervised learning protocols. In particular, by providing entropic-heterogeneous datasets to its various layers, we predict and quantify a new emergent phenomenon – that we term {\em layer’s cooperativeness} – where the interplay of dataset entropies across network’s layers enhances their retrieval capabilities Beyond those they would have without reciprocal influence. Naively we would expect layers trained with less informative datasets to develop smaller retrieval regions compared to those pertaining to layers that experienced more information: this does not happen and all the retrieval regions settle to the same amplitude, allowing for optimal retrieval performance globally. This cooperative dynamics marks a significant advancement in understanding emergent computational capabilities within disordered systems.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Machine Learning (stat.ML)
Infinite-temperature thermostats by energy localization in a nonequilibrium setup
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-07 20:00 EST
Michele Giusfredi, Stefano Iubini, Antonio Politi, Paolo Politi
Some lattice models having two conservation laws may display an equilibrium phase transition from a homogeneous (positive temperature - PT) to a condensed (negative temperature) phase, where a finite fraction of the energy is localized in a few sites. We study one such stochastic model in an out-of-equilibrium setup, where the ends of the lattice chain are attached to two PT baths. We show that localized peaks may spontaneously emerge, acting as infinite-temperature heat baths. The number $N_b$ of peaks is expected to grow in time $t$ as $N_b \sim \sqrt{\ln t}$, as a consequence of an effective freezing of the dynamics. Asymptotically, the chain spontaneously subdivides into three intervals: the two external ones lying inside the PT region; the middle one characterized by peaks superposed to a background lying along the infinite-temperature line. In the thermodynamic limit, the Onsager formalism allows determining the shape of the whole profile.
Statistical Mechanics (cond-mat.stat-mech)
30 pages, 13 figures
A microstructural model of transversely isotropic, fibre-reinforced hydrogels
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-07 20:00 EST
Matthew G. Hennessy, Tom Shearer, Axel C. Moore
Fibre-reinforced hydrogels are promising materials for biomedical applications due to their strength, toughness, and tunability. However, it remains unclear how to design fibre-reinforced hydrogels for use in specific applications due to the lack of a flexible modelling framework that can predict and hence optimise their behaviour. In this paper, we present a microstructural model for transversely isotropic fibre-reinforced hydrogels that captures the specific geometry of the fibre network. The model also accounts for slack in the initial fibre network that is gradually removed upon deformation. The mechanical model for the fibre network is coupled to a nonlinear poroelastic model for the hydrogel matrix that accounts for osmotic stress. By comparing the model predictions to data from load-controlled, unconfined compression experiments, we show that the model can capture J-shaped stress-strain curves and time-dependent creep responses. We showcase how the model can be used to guide the design of materials for artificial cartilage by exploring how to maximise interstitial fluid pressure. We find that fluid pressurisation can be increased by using stiffer fibres, removing slack from the fibre network, and reducing the Young’s modulus of the hydrogel matrix. Finally, an open-source Python package has been developed for simulating unconfined compression experiments using the model.
Soft Condensed Matter (cond-mat.soft)
Accurate predictive model of band gap with selected important features based on explainable machine learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
In the rapidly advancing field of materials informatics, nonlinear machine learning models have demonstrated exceptional predictive capabilities for material properties. However, their black-box nature limits interpretability, and they may incorporate features that do not contribute to, or even deteriorate, model performance. This study employs explainable ML (XML) techniques, including permutation feature importance and the SHapley Additive exPlanation, applied to a pristine support vector regression model designed to predict band gaps at the GW level using 18 input features. Guided by XML-derived individual feature importance, a simple framework is proposed to construct reduced-feature predictive models. Model evaluations indicate that an XML-guided compact model, consisting of the top five features, achieves comparable accuracy to the pristine model on in-domain datasets while demonstrating superior generalization with lower prediction errors on out-of-domain data. Additionally, the study underscores the necessity for eliminating strongly correlated features to prevent misinterpretation and overestimation of feature importance before applying XML. This study highlights XML’s effectiveness in developing simplified yet highly accurate machine learning models by clarifying feature roles.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
9 pages, 4 figures, SI is included
Tuning Magnetism of Metal-Organic Framework by Different Types of Pressure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Shuang Liu, Na Su, Huixia Fu, Yan Liu, Young Sun
The properties of metal-organic frameworks (MOFs) are expected to be sensitive to external pressures because of their inherently flexible structures. Although pressure-driven structural transitions have been intensively studied, the influence of pressure on magnetism has been less exploited for MOFs. Especially, the efficiency of applied pressure may strongly depend on the pressure-transmitting medium (PTM) which may have a complex interaction with MOFs. Here, we report the distinctive effects of different types of pressure, including isotropic hydrostatic pressure, quasi-hydrostatic pressure, and uniaxial pressure, on the anisotropic magnetism of the perovskite MOF, [CH3NH3][Co(COOH)3]. It is found that the hydrostatic pressure has the minimal effect whereas the uniaxial pressure has the highest efficiency in tuning magnetization and magnetic anisotropy of the MOF. First-principles calculations reveal that the applied low pressures (less than 11 kbar) do not induce notable lattice distortion in the framework or the superexchange path. Instead, the modulation of hydrogen bonds is identified as a critical factor for pressure tuning of magnetization and anisotropy. These findings underscore the potential applications of directional pressure in precisely controlling the magnetic and electronic properties of MOFs.
Materials Science (cond-mat.mtrl-sci)
Detection of 2D SPT Order with Partial Symmetries
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
Alex Turzillo, Naren Manjunath, Jose Garre-Rubio
A method of using partial symmetries to distinguish two dimensional symmetry protected topological (SPT) phases of on-site, unitary symmetries is proposed. This novel order parameter takes a wavefunction, such as a ground state of a lattice model, and detects its SPT invariants as expectation values of finitely supported operators, without the need for flux insertion. The construction exploits the rotational symmetry of the lattice to extract on-site SPT invariants, building upon prior work on probing crystalline SPT phases with partial rotations. The method is demonstrated by computing the order parameter analytically on group cohomology models and numerically on a family of states interpolating between the CZX state and a trivial state. Its robustness is suggested by interpreting partial symmetries as generating the topological partition functions of lens spaces.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Synthetic and cosmological axion hybridization: entangled photons, (HBT) and quantum beats
New Submission | Other Condensed Matter (cond-mat.other) | 2025-03-07 20:00 EST
In this article it is argued that synthetic axions, emergent collective excitations in topological insulators or Weyl semimetals hybridize with the cosmological axion, a compelling dark matter candidate via a common two photon decay channel since they both couple to electromagnetic fields via a Chern-Simons term. We point out an analogy to a V-type three level system with the two upper levels identified with the synthetic and cosmological axions decaying into a two-photon state. The Weisskopf-Wigner theory of spontaneous decay in multi level atoms is complemented and extended to describe the dynamics of hybridization. The final two-photon state features both kinematic and polarization entanglement and displays quantum beats as a consequence of the interference between the decay paths. An initial population of either axion induces a population of the other via hybridization. Consequently, a dark matter axion condensate induces a condensate of the synthetic axion, albeit with small amplitude. We obtain a momentum and polarization resolved Hanbury- Brown Twiss (HBT) second order coherence describing coincident correlated two-photon detection. It exhibits quantum beats with a frequency given by the difference between the energies of the synthetic and cosmological axion and \emph{perhaps may be harnessed} to detect either type of axion excitations. The case of synthetic axions individually is obtained in the limit of vanishing coupling of the cosmological axion and features similar two-photon correlations. Hence second order (HBT) two-photon coherence \emph{may} provide an alternative detection mechanism for emergent condensed matter axionic collective excitations. Similarities and differences with parametrically down converted photons are discussed.
Other Condensed Matter (cond-mat.other), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
37 pages, 4 figures
Unraveling Antagonistic Collision-Controlled Reactivity in Energetic Molecular Perovskites with Deep Potential Molecular Dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Ming-Yu Guo, Yun-Fan Yan, Pin Chen, Wei-Xiong Zhang
The precise regulation of chemical decompositions in energetic materials, whether towards rapid ignition or stable endurance, requires atomic-scale principles governing reactivity, which remain elusive yet. Herein, we resolve this challenge through deep potential molecular dynamics (DPMD) simulations, uncovering a universal collision-control principle in energetic molecular perovskites, $\text{(H}{2}\text{dabco)B(ClO}{4}\text{)}{3}$, where $\text{H}{2}\text{dabco}^{2+}$ = 1,4-diazabicyclo[2.2.2]octane-1,4-diium, B = $\text{Na}^{+}$, $\text{K}^{+}$, $\text{Rb}^{+}$, $\text{NH}{4}^{+}$ for DAP-1, DAP-2, DAP-3 and DAP-4, respectively. Atomic-scale simulation with Arrhenius fitting for over 100-ps trajectories reveals that increasing B-site ionic radius ($\text{Na}^{+} < \text{K}^{+} < \text{Rb}^{+}$) simultaneously reduces both activation energy $E_{a}$, which enhances reactivity, and pre-exponential factor $A$ which suppresses collision probabilities for hydrogen transfer between site $X$ and site $A$, with sharply opposing kinetic consequences. This duality well explains the peak stability and insensitivity in $\text{K}^{+}$-based DAP-2, which optimally balance thermal endurance and collision dissipation. For ammonium-based DAP-4, though the radius of $\text{NH}_{4}^{+}$ is close to $\text{K}^{+}$, the reactive B-site cation triggers proton transfer that promotes $\text{C-H}$ bond rupture. By linking static cation radii to dynamic $E_{a}$-ln$(A)$ coupling, we rationalize non-monotonic decomposition temperatures ($\text{K}^{+} > \text{NH}{4}^{+} > \text{Rb}^{+} > \text{Na}^{+}$) macroscopic stability and establishes cornerstones for universal energetic material design.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Reversal of tracer advection and Hall drift in an interacting chiral fluid
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-07 20:00 EST
Erik Kalz, Shashank Ravichandir, Johannes Birkenmeier, Ralf Metzler, Abhinav Sharma
Chiral fluids are defined by broken mirror or time-reversal symmetry, giving rise to tensorial transport coefficients with antisymmetric components. A key example is the odd mobility tensor, which governs the response of a chiral tracer to an applied force and induces a characteristic transverse drift. While this response is well understood in the infinite dilution limit, the impact of interparticle interactions on the tracer dynamics remains largely unexplored. Here, we conduct an analytical and computational study of a chiral fluid with interparticle interactions and show that, under an external driving force, a chiral tracer can undergo a complete reversal of both its transverse Hall drift and its advection along the force. This reversal emerges from the interplay between odd mobility and interaction-mediated forces, resulting in a phenomenon reminiscent of absolute negative mobility.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Coexistence of distinct mobility edges in a 1D quasiperiodic mosaic model
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-03-07 20:00 EST
Xu Xia, Weihao Huang, Ke Huang, Xiaolong Deng, Xiao Li
We introduce a one-dimensional quasiperiodic mosaic model with analytically solvable mobility edges that exhibit different phase transitions depending on the system parameters. Specifically, by combining mosaic quasiperiodic next-nearest-neighbor hoppings and quasiperiodic on-site potentials, we rigorously demonstrate the existence of two distinct types of mobility edges: those separating extended and critical states, and those separating extended and localized states. Using Avila’s global theory, we derive exact analytical expressions for these mobility edges and determine the parameter regimes where each type dominates. Our numerical calculations confirm these analytical results through fractal dimension analysis. Furthermore, we propose an experimentally feasible scheme to realize this model using Bose-Einstein condensates in optical lattices with engineered momentum-state transitions. We also investigate the effects of many-body interactions under mean-field approximation. Our work provides a fertile ground for studying the coexistence of different types of mobility edges in quasiperiodic systems and suggests a feasible experimental platform to observe and control these transitions.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Gases (cond-mat.quant-gas)
5 pages, 3 figures. Comments are welcome
The Bose polaron as thermometer of a trapped Bose gas: a quantum Monte Carlo study
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-03-07 20:00 EST
Tomasz Wasak, Gerard Pascual, Gregory E. Astrakharchik, Jordi Boronat, Antonio Negretti
Quantum impurities interacting with quantum environments offer unique insights into many-body systems. Here, we explore the thermometric potential of a neutral impurity immersed in a harmonically trapped bosonic quantum gas below the Bose-Einstein condensation critical temperature $T_c$. Using ab-initio Path Integral Monte Carlo simulations at finite temperatures, we analyze the impurity’s sensitivity to temperature changes by exploiting experimentally accessible observables such as its spatial distribution. Our results, covering a temperature range of $-1.1 \leqslant T/T_c \leqslant 0.9$, reveal that the impurity outperforms estimations based on a one-species bath at lower temperatures, achieving relative precision of 3-4% for 1000 measurement repetitions. While non-zero boson-impurity interaction strength $g_{BI}$ slightly reduces the accuracy, the impurity’s performance remains robust, especially in the low-temperature regime $T/T_c \lesssim 0.45$ withing the analyzed interaction strengths $0 \leqslant g_{BI}/g \leqslant 5$, where $g$ is the boson-boson coupling. We confirm that quantum optical models can capture rather well the dependence of the temperature sensor on the impurity-gas interaction. Although our findings are in qualitative agreement with previous studies, our Monte Carlo simulations offer improved precision. We find that the maximum likelihood estimation protocol approaches the precision comparable to the limit set by the Quantum Fisher Information bound. Finally, using the Hellinger distance method, we directly extract the Fisher information and find that, by exploiting the extremum order statistics, impurities far from the trap center are more sensitive to thermal effects than those close to the trap center.
Quantum Gases (cond-mat.quant-gas)
19 pages, 6 figures
Nonlinear electron-phonon interactions in Migdal-Eliashberg theory
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-07 20:00 EST
Ingvar Zappacosta, Matthew Houtput, Jacques Tempere
Superconducting systems based on attractive electron-phonon interactions are the ones which are best understood at a fundamental level. They are well described using Eliashberg theory, which, unlike BCS theory, explicitly takes into account phonon dynamics. It is most often assumed that only linear electron-phonon interactions are relevant. However, for some superconductors like MgB$_2$ or hydride based superconductors, nonlinear electron-phonon interactions are known to contribute significantly, which is not taken into account in conventional Eliashberg theory. We provide a modification to Eliashberg theory by introducing nonlinear electron-phonon interactions. We show that the Eliashberg equations remain unchanged apart from a nonlinear extension of the Eliashberg spectral function. This extended spectral function can be used as a baseline for future ab initio calculations. We use it to construct an analytical toy model and show that the nonlinear electron-phonon coupling affects the superconducting gap function on the imaginary and real axis and causes an increase in the superconducting critical temperature.
Superconductivity (cond-mat.supr-con)
Obstacle-Induced Gurzhi Effect and Hydrodynamic Electron Flow in Two-Dimensional Systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
A. D. Levin, G. M. Gusev, V. A. Chitta, Z. D. Kvon, A. S. Jaroshevich, D. E. Utkin, D. V. Dmitriev, A. K. Bakarov
The viscous flow of electrons in a narrow channel requires both strong electron-electron interactions and no-slip boundary conditions. However, introducing obstacles within the liquid can significantly increase flow resistance and, as a result, amplify the effects of viscosity. Even in samples with smooth walls, the presence of an obstacle can strongly alter electron behavior, leading to pronounced hydrodynamic effects. We investigated transport in mesoscopic samples containing a disordered array of obstacles. In contrast to samples without obstacles, which do not show a decrease in resistivity with rising temperature, samples with obstacles exhibit a significant resistivity reduction as temperature increases (the Gurzhi effect). By measuring the negative magnetoresistance, we extracted shear viscosity and other parameters through comparison with theoretical predictions. Consequently, narrow-channel samples with a disordered obstacle array provide a valuable platform for studying hydrodynamic electron flow independently of boundary conditions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 6 figures
Physical Review B, 111, 125302 (2025)
Numerical investigation of the Brownian $q=2$ Potts Model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-07 20:00 EST
In active matter, such as the Vicsek Model of flocking, particles possesses an internal degree of freedom, such as their director, which is subject to interaction with other particles, provided they are within a certain range. In an effort to understand better the interplay between spatial and internal degrees of freedom, we study numerically a variation of the $q=2$ Potts Model on and off the lattice, where particles are additionally subject to Brownian motion. The lack of a feedback of the internal degrees of freedom to the spatial degrees of freedom renders this model generically non-equilibrium. We confirm previous work that showed that the static exponents of the phase transition are unaffected by the diffusion. In contrast to previous work, we show that the formation of ordered clusters is not undermined by diffusion, but should rather be thought of as an effective form of interaction. We demonstrate how our numerical findings can be understood on the basis of the well-established Model A, B and C: Off lattice, the Brownian $q=2$ Potts Model is Model C. On the lattice, it is Model A with an additional (irrelevant, conserved) Model B noise.
Statistical Mechanics (cond-mat.stat-mech)
Currernt Flow Mapping in Conducting Ferroelectric Domain Walls using Scanning NV-Magnetometry
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Conor J. McCluskey, James Dalzell, Amit Kumar, J. Marty Gregg
The electrical conductivity of parallel plate capacitors, with ferroelectric lithium niobate as the dielectric layer, can be extensively and progressively modified by the controlled injection of conducting domain walls. Domain wall-based memristor devices hence result. Microstructures, developed as a result of partial switching, are complex and so simple models of equivalent circuits, based on the collective action of all conducting domain wall channels acting identically and in parallel, may not be appropriate. Here, we directly map the current density in ferroelectric domain wall memristors in-situ, by mapping Oersted fields, using nitrogen vacancy centre microscopy. Current density maps were found to directly correlate with the domain microstructure, revealing that a strikingly small fraction of the total domain wall network is responsible for the majority of the current flow. This insight forces a two order of magnitude correction to the carrier densities, previously inferred from standard scanning probe or macroscopic electrical characterisation.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Main Text: 19 Pages, 4 Figures. Supplementary Information: 7 Pages, 3 Figures
Sign reversal of Berry curvature triple driven by magnetic phase transition in a ferromagnetic polar metal
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Xuyang Sha, Xuejin Zhang, Hao Liu, Jin Cao, Ruohan Chen, Jinfeng Zhai, Dingfu Shao, Shiwei Wu, Cong Xiao, Shengyuan A. Yang, Pan He, Hangwen Guo, Jian Shen
Nonlinear Hall effects have been observed in quantum materials where Berry curvature and its momentum-space derivatives, such as the Berry curvature dipole (BCD) and Berry curvature triple (BCT), play a central role. While inversion symmetry breaking is widely recognized as a key criterion, the impact of time-reversal symmetry breaking remains less explored. Here, we report an abrupt enhancement of nonlinear Hall conductivity in non-centrosymmetric SrRuO3 (111) thin films during the paramagnetic-to-ferromagnetic transition. Scaling analysis reveals a sign reversal of the skew scattering contribution upon time-reversal symmetry breaking, which we attribute to the sign reversal of BCT at the Fermi surface. Density functional theory (DFT) calculations support this interpretation, showing the spin-polarized band splitting shifts the Fermi level asymmetrically for different spin channels. Our findings establish SrRuO3 (111) thin films as a promising platform for exploring magnetically tunable nonlinear transport effects.
Materials Science (cond-mat.mtrl-sci)
Surface-dominant transport in Weyl semimetal NbAs nanowires for next-generation interconnects
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
Yeryun Cheonj, Mehrdad T. Kiani, Yi-Hsin Tu, Sushant Kumar, Nghiep Khoan Duong, Jiyoung Kim, Quynh P. Sam, Han Wang, Satya K. Kushwaha, Nicolas Ng, Seng Huat Lee, Sam Kielar, Chen Li, Dimitrios Koumoulis, Saif Siddique, Zhiqiang Mao, Gangtae Jin, Zhiting Tian, Ravishankar Sundararaman, Hsin Lin, Gengchiau Liang, Ching-Tzu Chen, Judy J. Cha
Ongoing demands for smaller and more energy efficient electronic devices necessitate alternative interconnect materials with lower electrical resistivity at reduced dimensions. Despite the emergence of many promising candidates, synthesizing high quality nanostructures remains a major bottleneck in evaluating their performance. Here, we report the successful synthesis of Weyl semimetal NbAs nanowires via thermomechanical nanomolding, achieving single crystallinity and controlled diameters as small as 40 nm. Our NbAs nanowires exhibit a remarkably low room-temperature resistivity of 9.7 +/- 1.6 microOhm-cm, which is three to four times lower than their bulk counterpart. Theoretical calculations corroborate the experimental observations, attributing this exceptional resistivity reduction to surface dominant conduction with long carrier lifetime at finite temperatures. Further characterization of NbAs nanowires and bulk single crystals reveals high breakdown current density, robust stability, and superior thermal conductivity. Collectively, these properties highlight the strong potential of NbAs nanowires as next-generation interconnects, which can surpass the limitations of current copper-based interconnects. Technologically, our findings present a practical application of topological materials, while scientifically showcasing the fundamental properties uniquely accessible in nanoscale platforms.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
5 figures
Annihilation-limited Long-range Exciton Transport in High-mobility Conjugated Copolymer Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Yuping Shi, Partha Roy, Naoki Higashitarumizue, Tsung-Yen Lee, Quanwei Li, Ali Javeye, Katharina Landfester, Iain McCullochh, Graham Fleming
A combination of ultrafast, long-range and low-loss excitation energy transfer from the photo-receptor location to a functionally active site is essential for cost-effective polymeric semiconductors. Delocalized electronic wavefunctions along {\pi}-conjugated polymer backbone can enable efficient intrachain transport, while interchain transport is generally thought slow and lossy due to weak chain-chain interactions. In contrast to the conventional strategy of mitigating structural disorder, amorphous layers of rigid conjugated polymers, exemplified by highly planar poly(indacenodithiophene-co-benzothiadiazole) (IDT-BT) donor-accepter copolymer, exhibit trap-free transistor performance and charge-carrier mobilities similar to amorphous silicon. Here we report long-range exciton transport in HJ-aggregated IDTBT thin-film, in which the competing exciton transport and exciton-exciton annihilation (EEA) dynamics are spectroscopically separated using a phase-cycling-based scheme and shown to depart from the classical iffusion-limited and strong-coupling regime. In the thin film, we find an annihilation-limited mechanism with a per-encounter annihilation probability of much less than 100%, facilitating the minimization of EEA-induced excitation losses. In contrast, excitons on isolated IDTBT chains diffuse over 350 nm with 0.56 cm2 s-1 diffusivity, before eventually annihilating with unit probability on first contact. We complement the pump-probe studies with temperature dependent photocurrent and EEA measurements from 295 K to 77 K and find a remarkable correspondence of annihilation rate and photocurrent activation energies in the 140 K to 295 K temperature range.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft), Adaptation and Self-Organizing Systems (nlin.AO), Chemical Physics (physics.chem-ph)
This is a journal(PNAS) accepted version
PNAS 2025
Quantum spin liquid ground state in a rare-earth triangular antiferromagnet SmTa$7$O${19}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
Dhanpal Bairwa, Abhisek Bandyopadhyay, Devashibhai Adroja, G. B. G. Stenning, Hubertus Luetkens, Thomas James Hicken, Jonas A. Krieger, G. Cibin, M. Rotter, S. Rayaprol, P. D. Babu, Suja Elizabeth
The rare-earth-based geometrically frustrated triangular magnets have attracted considerable attention due to the intricate interplay between strong spin-orbit coupling and the crystal electric field (CEF), which often leads to effective spin-1/2 degrees of freedom and therefore promotes strong quantum fluctuations at low temperatures, thus offering an excellent route to stabilize a quantum spin liquid (QSL) ground state. We have investigated the ground state magnetic properties of a polycrystalline sample of $\text{SmTa}7\text{O}{19}$ which we propose to have a gapless QSL ground state by employing powder X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), DC and AC-magnetic susceptibility, $M$ vs. $H$ isotherm, specific heat, and muon spin rotation/relaxation measurements ($\mu$SR) down to 30 mK. The combined structural and electronic studies reveal the formation of an edge-sharing equilateral triangular lattice of Sm$^{3+}$ ions in $ab$ plane. The DC, AC magnetic susceptibility, and heat capacity measurements reveal that $\text{SmTa}7\text{O}{19}$ does not exhibit any long-range magnetic ordering transition down to 50 mK. The zero-field (ZF)-$\mu$SR study strongly refutes the long-range magnetically ordered ground state and/or any partial spin-freezing down to at least 30 mK. The ZF-muon-spin relaxation rate is weakly temperature dependent between 50 and 20 K, rapidly increases below $\sim$20 K and saturates at low temperatures between 2 K and 30 mK, which has been attributed to a characteristic signature of QSL systems. Further, our longitudinal-field (LF)-$\mu$SR measurements at 0.1 K reveal a dynamic nature of the magnetic ground state. In addition, our high-field specific heat data suggest a gapless nature of spin excitations in this compound.
Strongly Correlated Electrons (cond-mat.str-el)
23 pages and 14 figures
Spin-strain interactions under hydrostatic pressure in $α$-RuCl$_3$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
A. Hauspurg, Susmita Singh, T. Yanagisawa, V. Tsurkan, J. Wosnitza, Wolfram Brenig, Natalia B. Perkins, S. Zherlitsyn
We investigate the effects of hydrostatic pressure on $\alpha$-RuCl$_3$, a prototypical material for the Kitaev spin model on a honeycomb lattice with a possible spin-liquid ground state. Using ultrasound measurements at pressures up to 1.16 GPa, we reveal significant modifications of the acoustic properties and the $H$-$T$ phase diagram of this material. Hydrostatic pressure suppresses the three-dimensional magnetic order and induces a dimerization transition at higher pressures. At low pressures, the sound attenuation exhibits a linear temperature dependence, while above 0.28 GPa, it becomes nearly temperature independent, suggesting a shift in the phonon scattering regime dominated by Majorana fermions. These findings provide new insights into spin-strain interactions in Kitaev magnets and deliver a detailed characterization of the $H$-$T$ phase diagram of $\alpha$-RuCl$_3$ under hydrostatic pressure.
Strongly Correlated Electrons (cond-mat.str-el)
Quench of the electronic order in a strongly-coupled charge-density-wave system by enhanced lattice fluctuations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-07 20:00 EST
Manuel Tuniz, Denny Puntel, Wibke Bronsch, Francesco Sammartino, Gian Marco Pierantozzi, Riccardo Cucini, Fulvio Parmigiani, Federico Cilento
Charge-density-wave (CDW) materials having a strong electron-phonon coupling provide a powerful platform for investigating the intricate interplay between lattice fluctuations and a macroscopic quantum order. Using time- and angle-resolved photoemission spectroscopy (TR-ARPES), we reveal that the CDW gap closure in VTe2 is dominated by an incoherent process evolving on a sub-picosecond timescale, challenging the conventional view that the gap dynamics is primarily governed by the excitation of the CDW amplitude modes. Our findings, supported by a three-temperature model, show that the CDW gap evolution can be described by considering the population of a subset of strongly-coupled optical phonon modes, which leads to an increase in the lattice fluctuations. This microscopic framework extends beyond VTe2, offering a universal perspective for understanding the light-induced phase transition in strongly-coupled CDW systems.
Strongly Correlated Electrons (cond-mat.str-el)
Predicting Heteropolymer Phase Separation Using Two-Chain Contact Maps
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-07 20:00 EST
Jessica Jin, Wesley Oliver, Michael A. Webb, William M. Jacobs
Phase separation in polymer solutions often correlates with single-chain and two-chain properties, such as the single-chain radius of gyration, Rg, and the pairwise second virial coefficient, B22. However, recent studies have shown that these metrics can fail to distinguish phase-separating from non-phase-separating heteropolymers, including intrinsically disordered proteins (IDPs). Here we introduce an approach to predict heteropolymer phase separation from two-chain simulations by analyzing contact maps, which capture how often specific monomers from the two chains are in physical proximity. Whereas B22 summarizes the overall attraction between two chains, contact maps preserve spatial information about their interactions. To compare these metrics, we train phase-separation classifiers for both a minimal heteropolymer model and a chemically specific, residue-level IDP model. Remarkably, simple statistical properties of two-chain contact maps predict phase separation with high accuracy, vastly outperforming classifiers based on Rg and B22 alone. Our results thus establish a transferable and computationally efficient method to uncover key driving forces of IDP phase behavior based on their physical interactions in dilute solution.
Soft Condensed Matter (cond-mat.soft), Biomolecules (q-bio.BM)
QE-CONVERSE: An open-source package for the Quantum ESPRESSO distribution to compute non-perturbatively orbital magnetization from first principles, including NMR chemical shifts and EPR parameters
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-07 20:00 EST
Simone Fioccola, Luigi Giacomazzi, Davide Ceresoli, Layla Martin-Samos, Anne Hemerick, Nicolas Richard
Orbital magnetization, a key property arising from the orbital motion of electrons, plays a crucial role in determining the magnetic behavior of molecules and solids. Despite its straightforward calculation in finite systems, the computation in periodic systems poses challenges due to the ill-defined position operator and surface current contributions. The modern theory of orbital magnetization, implemented in the Density Functional Theory (DFT) framework, offers an accurate solution via the “converse approach.” Here, we introduce QE-CONVERSE, a refactored, modular implementation of this method, replacing outdated routines from Quantum ESPRESSO (version 3.2). QE-CONVERSE integrates modern computational libraries like scaLAPACK and ELPA, enhancing scalability, especially for large supercell calculations. This work focuses on providing the community with a reliable, accurate orbital magnetization package for properties such as Electron Paramagnetic Resonance (EPR) g-tensors and Nuclear Magnetic Resonance (NMR) chemical shifts, particularly where perturbative methods fail. We demonstrate QE-CONVERSE’s effectiveness with benchmark cases, including the NMR shifts of ${}^{27}$Al in alumina and ${}^{17}$O and ${}^{29}$Si in $\alpha$-quartz, as well as the EPR g-tensor for $_{ }^{n}\Sigma(n\geq 2)$ radicals and nitrogen defects in silicon. Results show excellent agreement with theoretical and experimental data, with improved accuracy in EPR calculations over linear response methods. QE-CONVERSE is fully compatible with recent Quantum ESPRESSO versions, enabling new possibilities for studying complex materials
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
Integrability and charge transport in asymmetric quantum-circuit geometries
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-07 20:00 EST
Chiara Paletta, Urban Duh, Balázs Pozsgay, Lenart Zadnik
We revisit the integrability of quantum circuits constructed from two-qubit unitary gates $U$ that satisfy the Yang-Baxter equation. A brickwork arrangement of $U$ typically corresponds to an integrable Trotterization of some Hamiltonian dynamics. Here, we consider more general circuit geometries which include circuits without any nontrivial space periodicity. We show that any time-periodic quantum circuit in which $U$ is applied to each pair of neighbouring qubits exactly once per period remains integrable. We further generalize this framework to circuits with time-varying two-qubit gates. The spatial arrangement of gates in the integrable circuits considered herein can break the space-reflection symmetry even when $U$ itself is symmetric. By analyzing the dynamical spin susceptibility on ballistic hydrodynamic scale, we investigate how an asymmetric arrangement of gates affects the spin transport. While it induces nonzero higher odd moments in the dynamical spin susceptibility, the first moment, which corresponds to a drift in the spreading of correlations, remains zero. We explain this within a quasiparticle picture which suggests that a nonzero drift necessitates gates acting on distinct degrees of freedom.
Statistical Mechanics (cond-mat.stat-mech)
23 pages, 13 figures
Characterizing $S=3/2$ AKLT Hamiltonian with Scanning Tunneling Spectroscopy
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-07 20:00 EST
M. Ferri-Cortés, J. C. G. Henriques, J. Fernández-Rossier
The AKLT Hamiltonian is a particular instance of a general class of model Hamiltonians defined in lattices with coordination $z$ where each site hosts a spins $S=z/2$, interacting both with linear and non-linear exchange couplings. In two dimensions, the AKLT model features a gap in the spectrum, and its ground state is a valence bond solid state; that is an universal resource for measurement based quantum computing, motivating the quest of physical systems that realize this Hamiltonian. Given a finite-size system described with a specific instance of this general class of models, we address the question of how to asses if such system is a realization of the AKLT model using inelastic tunnel spectroscopy implemented with scanning tunnel microscopy (IETS-STM). We propose two approaches. First, in the case of a dimer, we show how to leverage non-equilibrium IETS-STM to obtain the energies of all excited states, and determine thereby the magnitude of both linear and non-linear exchange interactions. Second, we explore how IETS can probe the in-gap excitations associated to edge spins. In the AKLT limit, spins $S=3/2$ at the edge of the lattice have coordination 2, giving rise to $S=1/2$ dangling spins that can be probed with IETS. We propose a $S=1/2$ effective Hamiltonian to describe the interactions between these dangling spins in the neighborhood of the AKLT point, where their degeneracy lifted.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Capacitive response of biological membranes
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-07 20:00 EST
Jafar Farhadi, Joshua B. Fernandes, Karthik Shekhar, Kranthi K. Mandadapu
We present a minimal model to analyze the capacitive response of a biological membrane subjected to a step voltage via blocking electrodes. Through a perturbative analysis of the underlying electrolyte transport equations, we show that the leading-order relaxation of the transmembrane potential is governed by a capacitive timescale, ${\tau_{\rm C} =\dfrac{\lambda_{\rm D}L}{D}\left(\dfrac{2+\Gamma\delta^{\rm M}/L}{4+\Gamma\delta^{\rm M}/\lambda_{\rm D}}\right)}$, where $\lambda_{\rm D}$ is the Debye screening length, $L$ is the electrolyte width, $\Gamma$ is the ratio of the dielectric permittivity of the electrolyte to the membrane, $\delta^{\rm M}$ is the membrane thickness, and $D$ is the ionic diffusivity. This timescale is considerably shorter than the traditional RC timescale ${\lambda_{\rm D} L / D}$ for a bare electrolyte due to the membrane’s low dielectric permittivity and finite thickness. Beyond the linear regime, however, salt diffusion in the bulk electrolyte drives a secondary, nonlinear relaxation process of the transmembrane potential over a longer timescale ${\tau_{\rm L} =L^2/4\pi^2 D}$. A simple equivalent-circuit model accurately captures the linear behavior, and the perturbation expansion remains applicable across the entire range of observed physiological transmembrane potentials. Together, these findings underscore the importance of the faster capacitive timescale and nonlinear effects on the bulk diffusion timescale in determining transmembrane potential dynamics for a range of biological systems.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Subcellular Processes (q-bio.SC)
Origin and emergent features of many-body dynamical localization
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-03-07 20:00 EST
Ang Yang, Zekai Chen, Yanliang Guo, Manuele Landini, Hanns-Christoph Nägerl, Lei Ying
The question of whether interactions can break dynamical localization in quantum kicked rotor systems has been the subject of a long-standing debate. Here, we introduce an extended mapping from the kicked Lieb-Liniger model to an effective lattice model with long-range couplings and reveal two universal features: on-site pseudorandomness and rapidly decaying couplings in the center-of-mass momentum. For finite contact interactions, the long-range coupling between relative momenta obeys an algebraic decay behavior with a crossover of its decay exponent as the interaction increases. Similar behavior occurs in the Fock basis, underscoring the robustness and distinct many-body characteristics of dynamical localization. Analysis of the generalized fractal dimension and level-spacing ratio also supports these findings, highlighting the presence of near integrability and multifractality in different regions of parameter space. Our results offer an explanation for the occurrence of many-body dynamical localization, particularly in strongly correlated quantum gases, and are anticipated to generalize to systems of many particles.
Quantum Gases (cond-mat.quant-gas)
18 pages, 14 figures