CMP Journal 2025-02-24
Statistics
Nature Materials: 3
Nature Nanotechnology: 1
Nature Physics: 2
Physical Review Letters: 3
Physical Review X: 2
Review of Modern Physics: 1
arXiv: 53
Nature Materials
Electrochemiluminescent tactile visual synapse enabling in situ health monitoring
Original Paper | Electrical and electronic engineering | 2025-02-23 19:00 EST
Woojoong Kim, Kyuho Lee, Sanghyeon Choi, Eunje Park, Gwanho Kim, Jebong Ha, Yeeun Kim, Jihye Jang, Ji Hye Oh, HoYeon Kim, Wei Jiang, Jioh Yoo, Taebin Kim, Yeonji Kim, Kwan-Nyeong Kim, Juntaek Hong, Ali Javey, Dong-wook Rha, Tae-Woo Lee, Keehoon Kang, Gunuk Wang, Cheolmin Park
Tactile visual synapses combine the functionality of tactile artificial synapses with the ability to visualize their activity in real time and provide a direct and intuitive visualization of the activity, offering an efficient route for in situ health monitoring. Herein we present a tactile visual synapse that enables in situ monitoring of finger rehabilitation and electrocardiogram analysis. Repetitive finger flexion and various arrhythmias are monitored and visually guided using the developed tactile visual synapse combined with an electrical and optical output feedback algorithm. The tactile visual synapse has the structure of an electrochemical transistor comprising an elastomeric top gate as a tactile receptor and an electrochemiluminescent ion gel as a light-emitting layer stacked on a polymeric semiconductor layer, forming an electrical synaptic channel between source and drain electrodes. The low-power (~34 μW) visualization of the tactile synaptic activity associated with the repetitive motions of fingers and heartbeats enables the development of a convenient and efficient personalized healthcare system.
Electrical and electronic engineering, Electronic and spintronic devices, Electronic devices, Sensors and biosensors
On-patient medical record and mRNA therapeutics using intradermal microneedles
Original Paper | Biomaterials - vaccines | 2025-02-23 19:00 EST
Jooli Han, Maria Kanelli, Yang Liu, John L. Daristotle, Apurva Pardeshi, Timothy A. Forster, Ari Karchin, Brandon Folk, Lukas Murmann, Lisa H. Tostanoski, Sebastian E. Carrasco, Shahad K. Alsaiari, Erika Yan Wang, Khanh Tran, Linzixuan Zhang, Behnaz Eshaghi, Lauren Levy, Sydney Pyon, Charles Sloane, Stacey Qiaohui Lin, Alicia Lau, Collin F. Perkinson, Moungi G. Bawendi, Dan H. Barouch, Frédo Durand, Robert Langer, Ana Jaklenec
Medical interventions often require timed series of doses, thus necessitating accurate medical record-keeping. In many global settings, these records are unreliable or unavailable at the point of care, leading to less effective treatments or disease prevention. Here we present an invisible-to-the-naked-eye on-patient medical record-keeping technology that accurately stores medical information in the patient skin as part of microneedles that are used for intradermal therapeutics. We optimize the microneedle design for both a reliable delivery of messenger RNA (mRNA) therapeutics and the near-infrared fluorescent microparticles that encode the on-patient medical record-keeping. Deep learning-based image processing enables encoding and decoding of the information with excellent temporal and spatial robustness. Long-term studies in a swine model demonstrate the safety, efficacy and reliability of this approach for the co-delivery of on-patient medical record-keeping and the mRNA vaccine encoding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This technology could help healthcare workers make informed decisions in circumstances where reliable record-keeping is unavailable, thus contributing to global healthcare equity.
Biomaterials - vaccines, Biomedical materials, Nanoparticles
Roll-to-plate printable RGB achromatic metalens for wide-field-of-view holographic near-eye displays
Original Paper | Displays | 2025-02-23 19:00 EST
Minseok Choi, Joohoon Kim, Seokil Moon, Kilsoo Shin, Seung-Woo Nam, Yujin Park, Dohyun Kang, Gyoseon Jeon, Kyung-il Lee, Dong Hyun Yoon, Yoonchan Jeong, Chang-Kun Lee, Junsuk Rho
Metalenses show promise for replacing conventional lenses in virtual reality systems, thereby facilitating lighter and more compact near-eye displays (NEDs). However, at the centimetre scale necessary for practical applications, previous multiwavelength achromatic metalenses have faced challenges in mass production and exhibited a low numerical aperture (NA), which limits their practical application in NEDs. Here we introduce a centimetre-scale red, green and blue achromatic metalens fabricated using a roll-to-plate technique and explore its potential for practical applications in NEDs. This metalens is designed through topological inverse design utilizing a finite-difference time-domain simulation for entire areas (~10,000λ). Our design method demonstrates the ability to compensate chromatic aberrations even at the centimetre scale and high NA with low-index materials such as resin suitable for scalable manufacturing. In addition, we developed a compact NED by integrating the metalens with computer-generated holography (CGH). In this NED system, the high-NA metalens address the limitations of narrow field of view and extensive empty space typical of conventional CGH-based NEDs. The CGH optimization model further resolves the challenges of broadband operation and off-axis aberration in centimetre-scale red, green and blue achromatic metalenses.
Displays, Mathematics and computing, Metamaterials, Nanophotonics and plasmonics, Surface patterning
Nature Nanotechnology
Nanoscopic cross-grain cation homogenization in perovskite solar cells
Original Paper | Solar cells | 2025-02-23 19:00 EST
Mingwei Hao, Jonghee Yang, Wenjian Yu, Benjamin J. Lawrie, Pengfei Guo, Xiangzhao Zhang, Tianwei Duan, Tong Xiao, Linqi Chen, Yang Xiang, Peijun Guo, Mahshid Ahmadi, Yuanyuan Zhou
Multiscale cation inhomogeneity has been a major hurdle in state-of-the-art formamidinium-caesium (FA-Cs) mixed-cation perovskites for achieving perovskite solar cells with optimal power conversion efficiencies and durability. Although the field has attempted to homogenize the overall distributions of FA-Cs in perovskite films from both plan and cross-sectional views, our understanding of grain-to-grain cation inhomogeneity and ability to tailor it--that is, spatially resolving the FA-Cs compositional difference between individual grains down to the nanoscale--are lacking. Here we reveal that as fundamental building blocks of a perovskite film, individual grains exhibit cationic compositions deviating from the prescribed ideal composition, severely limiting the interfacial optoelectronic properties and perovskite layer durability. This performance-limiting nanoscopic factor is linked to thermodynamic-driven morphological grooving, leading to a segmented surface landscape. At the grain triple junctions, grooves form nanoscale groove traps that hinder the mixing of solid-state cations across grains and thus retard inter-grain FA-Cs mixing. By rationally modulating the heterointerfacial energies, we reduced the depth of these nanoscale groove traps by a factor of three, significantly improving cation homogeneity. Perovskite solar cells with shallower nanoscale groove traps demonstrate enhanced power conversion efficiencies (25.62%) and improved stability under various standardized international protocols. Our work highlights the significance of resolving surface nano-morphologies for homogeneous properties of perovskites.
Solar cells, Synthesis and processing
Nature Physics
Twist-torsion coupling in beating axonemes
Original Paper | Biological physics | 2025-02-23 19:00 EST
Martin Striegler, Stefan Diez, Benjamin M. Friedrich, Veikko F. Geyer
Motile cilia and flagella produce regular bending waves that enable single-cell navigation due to non-planar waveforms with characteristic torsion. However, it is not known how torsion, a geometric property of the three-dimensional waveform, relates to mechanical twist deformations of the axoneme, the conserved cytoskeletal core of cilia and flagella. Here we show that axoneme twisting and torsion are coupled and that twist waves propagate along the beating axoneme of Chlamydomonas reinhardtii algae. We resolve the three-dimensional shapes of the axonemal waveform with nanometre precision at millisecond timescales using defocused dark-field microscopy and beat-cycle averaging, observing regular hetero-chiral torsion waves propagating base to tip. To investigate whether the observed torsion results from axonemal twist, we attach gold nanoparticles to axonemes and measure their cross-section rotation during beating. We find that, locally, the axonemal cross-section co-rotates with the bending plane, evidencing twist-torsion coupling. Our results demonstrate the link between shape and mechanical deformation in beating axonemes and can inform models of the dynamics of motor proteins inside the axoneme responsible for shaping the beat of motile cilia.
Biological physics, Cellular motility, Motor protein tracks
Higher-order Laplacian renormalization
Original Paper | Complex networks | 2025-02-23 19:00 EST
Marco Nurisso, Marta Morandini, Maxime Lucas, Francesco Vaccarino, Tommaso Gili, Giovanni Petri
The renormalization group is a pillar of the theory of scaling, scale invariance and universality in physics. Recently, this tool has been adapted to complex networks with pairwise interactions through a scheme based on diffusion dynamics. However, as the importance of polyadic interactions in complex systems becomes more evident, there is a pressing need to extend the renormalization group methods to higher-order networks. Here we fill this gap and propose a Laplacian renormalization group scheme for arbitrary higher-order networks. At the heart of our approach is the introduction of cross-order Laplacians, which generalize existing higher-order Laplacians by allowing the description of diffusion processes that can happen on hyperedges of any order via hyperedges of any other order. This approach enables us to probe higher-order structures, define scale invariance at various orders and propose a coarse-graining scheme. We validate our approach on controlled synthetic higher-order systems and then use it to detect the presence of order-specific scale-invariant profiles of real-world complex systems from multiple domains.
Complex networks, Statistical physics
Physical Review Letters
Quantum Coulomb Drag Mediated by Cotunneling of Fluxons and Cooper Pairs
Research article | Dissipative dynamics | 2025-02-24 05:00 EST
Andrew G. Semenov, Alex Latyshev, and Andrei D. Zaikin
We predict two novel quantum drag effects which can occur in macroscopically quantum coherent Josephson circuits. We demonstrate that biasing one resistively shunted Josephson junction by an external current one can induce a nonzero voltage drop across another such junction capacitively coupled to the first one. This quantum Coulomb drag is caused by cotunneling of magnetic flux quanta across both junctions which remain in the ''superconducting'' regime. Likewise, Cooper pair cotunneling across a pair of connected in series Josephson junctions in the ''insulating'' regime is responsible for another---dual---quantum Coulomb drag effect.
Phys. Rev. Lett. 134, 086001 (2025)
Dissipative dynamics, Superconducting fluctuations, Superconducting phase transition, Superconductivity, Josephson junctions, Superconducting devices, Finite temperature field theory, Path integrals
Ground State of the \(S=1/2\) Heisenberg Spin Chain with Random Ferromagnetic and Antiferromagnetic Couplings
Research article | Antiferromagnetism | 2025-02-24 05:00 EST
Sibei Li, Hui Shao, and Anders W. Sandvik
We study the Heisenberg \(S=1/2\) chain with random ferro- and antiferromagnetic couplings using quantum Monte Carlo simulations at ultra-low temperatures, converging to the ground state. Finite-size scaling of correlation functions and excitation gaps demonstrate an exotic critical state in qualitative agreement with previous strong-disorder renormalization group calculations but with scaling exponents depending on the coupling distribution. We find dual scaling regimes of the transverse correlations versus the distance, with an \(L\) independent form \(C(r)={r}^{- \mu }\) for \(r\ll L\) and \(C(r,L)={L}^{- \eta }f(r/L)\) for \(r/L>0\), where $>$ and the scaling function is delivered by our analysis. These results are at variance with previous spin-wave and density-matrix renormalization group calculations, thus highlighting the power of unbiased quantum Monte Carlo simulations.
Phys. Rev. Lett. 134, 086501 (2025)
Antiferromagnetism, Exchange interaction, Ferrimagnetism, Spin dynamics, Spin waves, 1-dimensional spin chains, Finite-size scaling, Quantum Monte Carlo
Giant Strain-Induced Spin Splitting Effect in MnTe, a \(g\)-Wave Altermagnetic Semiconductor
Research article | Electronic structure | 2025-02-24 05:00 EST
K. D. Belashchenko
Hexagonal MnTe is an altermagnetic semiconductor with \(g\)-wave symmetry of spin polarization in momentum space. In the nonrelativistic limit, this symmetry mandates that electric current flowing in any crystallographic direction is unpolarized. However, here I show that elastic strain is effective in inducing the spin splitting effect in MnTe. For this analysis, a spin-orbit-coupled \(\mathbf{k}\cdot{}\mathbf{p}\) Hamiltonian for the valence band maximum at the A point is derived and fitted to eigenvalues calculated from first principles. The spin splitting angle is calculated using the Boltzmann approach in the relaxation-time approximation. The spin splitting gauge factor exceeds 30 near the valence band maximum. Thus, with suitable substrate engineering, MnTe can be used as an efficient source and detector of spin current in spintronic devices. Proper inclusion of the Rashba-Dresselhaus spin-orbit coupling is crucial for the correct description of the transport properties of MnTe.
Phys. Rev. Lett. 134, 086701 (2025)
Electronic structure, Rashba coupling, Spin Hall effect, Spintronics, Altermagnets, Antiferromagnets, First-principles calculations, k dot p method
Physical Review X
Multizone Trapped-Ion Qubit Control in an Integrated Photonics QCCD Device
Research article | Atomic, optical & lattice clocks | 2025-02-24 05:00 EST
Carmelo Mordini, Alfredo Ricci Vasquez, Yuto Motohashi, Mose Müller, Maciej Malinowski, Chi Zhang, Karan K. Mehta, Daniel Kienzler, and Jonathan P. Home
The demonstration that ions can be precisely manipulated in a trap containing integrated photonics paves the way for a large-scale trapped-ion quantum processor.
Phys. Rev. X 15, 011040 (2025)
Atomic, optical & lattice clocks, Coherent control, Integrated optics, Photonics, Quantum computing models, Quantum control, Quantum information architectures & platforms, Quantum information processing, Trapped ions, Waveguides, Transport techniques
Chaperone-Driven Entropic Separation of Amyloid Nanofilament Bundles
Research article | Biomolecular processes | 2025-02-24 05:00 EST
Jose M. G. Vilar, J. Miguel Rubi, and Leonor Saiz
New insight into how molecular chaperones break apart toxic protein deposits that form amyloid fibrils sheds light on strategies to target these deposits in diseases like Alzheimer's and Parkinson's.
Phys. Rev. X 15, 011041 (2025)
Biomolecular processes, Colloids, Macromolecules, Proteins, Brownian dynamics, Coarse graining
Review of Modern Physics
Wrinkles, creases, and cusps in growing soft matter
Research article | Biomechanics | 2025-02-24 05:00 EST
Martine Ben Amar
The buckling of a material surface subject to compression or growth is a ubiquitous phenomenon, arising in materials science contexts such as the swelling of gels as well as in biological contexts such as morphogenesis and embryogenesis. A complete understanding of the creases and sharp cusps that commonly accompany buckling requires nonlinear elasticity theory. This review presents a modern treatment of the Biot instability, integrating many standard techniques of nonlinear physics and solid mechanics, such as bifurcation theory, conformal mapping, and J and M integrals.
Rev. Mod. Phys. 97, 015004 (2025)
Biomechanics, Biological materials, Elastomers, Gels, Living matter & active matter, Polymer gels, Mathematical physics methods, Perturbation theory, Spatial modeling, Theories of collective dynamics & active matter
arXiv
Towards an automated workflow in materials science for combining multi-modal simulative and experimental information using data mining and large language models
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Balduin Katzer, Steffen Klinder, Katrin Schulz
To retrieve and compare scientific data of simulations and experiments in materials science, data needs to be easily accessible and machine readable to qualify and quantify various materials science phenomena. The recent progress in open science leverages the accessibility to data. However, a majority of information is encoded within scientific documents limiting the capability of finding suitable literature as well as material properties. This manuscript showcases an automated workflow, which unravels the encoded information from scientific literature to a machine readable data structure of texts, figures, tables, equations and meta-data, using natural language processing and language as well as vision transformer models to generate a machine-readable database. The machine-readable database can be enriched with local data, as e.g. unpublished or private material data, leading to knowledge synthesis. The study shows that such an automated workflow accelerates information retrieval, proximate context detection and material property extraction from multi-modal input data exemplarily shown for the research field of microstructural analyses of face-centered cubic single crystals. Ultimately, a Retrieval-Augmented Generation (RAG) based Large Language Model (LLM) enables a fast and efficient question answering chat bot.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
Incommensurate gapless ferromagnetism connecting competing symmetry-enriched deconfined quantum phase transitions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-24 20:00 EST
Anthony Rey, Ömer M. Aksoy, Daniel P. Arovas, Claudio Chamon, Christopher Mudry
Interpolating between distinct symmetry-enriched critical points is believed to require going through either a multicritical point or an intervening gapped phase. We present a scenario, in which a gapless extended phase serves as a "hub" connecting multiple symmetry-enriched deconfined quantum critical points. As a concrete example, we construct a lattice model with \(\mathbb{Z}^{\,}_{2}\times \mathbb{Z}^{\,}_{2}\times \mathbb{Z}^{\,}_{2}\) symmetry for quantum spin-1/2 degrees of freedom that realizes four distinct gapful phases supporting antiferromagnetic long-range order and one extended incommensurate gapless ferromagnetic phase. The quantum phase transition between any two of the four gapped and antiferromagnetic phases goes through either a (deconfined) quantum critical point, a quantum tricritical point, or the incommensurate gapless ferromagnetic phase. In this phase diagram, it is possible to interpolate between four deconfined quantum critical points by passing through the extended gapless ferromagnetic phase. We identify the phases in the model and the nature of the transitions between them through a combination of analytical arguments and density matrix renormalization group (DMRG) studies.
Strongly Correlated Electrons (cond-mat.str-el)
60 pages, 47 figures
Boundary Operator Product Expansion Coefficients of the Three-dimensional Ising Universality Class
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-24 20:00 EST
Dorian Przetakiewicz, Stefan Wessel, Francesco Parisen Toldin
Recent advances in field theory and critical phenomena have focused on the characterization of boundary or defects in a conformally-invariant system. In this Letter we study the critical behavior of the three-dimensional Ising universality class in the presence of a surface, realizing the ordinary, the special, and the normal universality classes. By using high-precision Monte Carlo simulations of an improved model, where leading scaling corrections are suppressed, and a finite-size scaling analysis, we determine unbiased, accurate estimates of universal boundary operator product expansion coefficients. Furthermore, we improve the value of the scaling dimension of the surface field at the special transition by the estimate \(\hat{\Delta}_\sigma = 0.3531(3)\).
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
37 pages, 1 figure, including Supplemental Material
Expanding the reach of diffusing wave spectroscopy and tracer bead microrheology
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
Manuel Helfer, Chi Zhang, Frank Scheffold
Diffusing Wave Spectroscopy (DWS) is an extension of standard dynamic light scattering (DLS), applied to soft materials that are turbid or opaque. The propagation of light is modeled using light diffusion, characterized by a light diffusion coefficient that depends on the transport mean free path lof the medium. DWS is highly sensitive to small particle displacements or other local fluctuations in the scattering properties and can probe subnanometer displacements. Analyzing the motion of beads in a viscoelastic matrix, known as one-bead microrheology, is one of the most common applications of DWS. Despite significant advancements since its invention in 1987, including two-cell and multi-speckle DWS, challenges such as merging single and multi-speckle data and limited accuracy for short correlation times persist. Here, we address these issues by improving the two-cell Echo DWS scheme. We propose a calibration-free method to blend and merge Echo and two-cell DWS data and demonstrate the use of regularized inversion algorithms to enhance data quality at very short times. Building on this, we introduce stable corrections for bead and fluid inertia, significantly improving the quality of microrheology data at high frequencies.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
14 pages, 5 figures, 4 supplementary figures
Time-periodic driving of a bath-coupled open quantum gas of light
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-24 20:00 EST
Andris Erglis, Alexander Sazhin, Frank Vewinger, Martin Weitz, Stefan Yoshi Buhmann, Julian Schmitt
We study the frequency-resolved density response of a photon Bose-Einstein condensate coupled to a bath of dye molecules by time-periodic driving. By monitoring the photon number dynamics for different drive frequencies, we obtain the spectral response of the condensate in a phase-sensitive way. We find that as the photon number increases, the response of the coupled condensate-bath system transitions from overdamped to resonant behavior, indicating a transition from closed to open system dynamics. Our spectroscopy method paves the way for studies of collective excitations in complex driven-dissipative systems.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
10 pages, 5 figures
Field Dislocation Mechanics, Conservation of Burgers vector, and the augmented Peierls model of dislocation dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Dissipative models for the quasi-static and dynamic response due to slip in an elastic body containing a single slip plane of vanishing thickness are developed. Discrete dislocations with continuously distributed cores can glide on this plane, and the models are developed as special cases of a fully three-dimensional theory of plasticity induced by dislocation motion. The reduced models are compared and contrasted with the augmented Peierls model of dislocation dynamics. A primary distinguishing feature of the reduced models is the a-priori accounting of space-time conservation of Burgers vector during dislocation evolution. A physical shortcoming of the developed models as well as the Peierls model with regard to a dependence on the choice of a distinguished, coherent reference configuration is discussed, and a testable model without such dependence is also proposed.
Materials Science (cond-mat.mtrl-sci), Classical Physics (physics.class-ph)
Magnetic Field-Controlled Mixed Modulation in Magnetoelectric Sensors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Elizaveta Spetzler, Benjamin Spetzler, Dennis Seidler, Johan Arbustini, Lars Thormählen, Robert Rieger, Andreas Bahr, Dirk Meyners, Jeffrey McCord
Magnetoelectric (ME) magnetic field sensors commonly rely on one of the two modulation principles: the nonlinear dependence of magnetostrictive strain on the applied field or the stress-induced change in magnetization susceptibility. While both effects coexist in any ME device, different readout schemes can be chosen to utilize one or the other effect for magnetic field sensing. This work demonstrates that both principles can be simultaneously implemented in a single electrically modulated ME sensor with inductive readout (a converse ME sensor). This mixed modulation approach significantly enhances low-frequency sensitivity while not affecting the sensitivity at higher frequencies. This leads to a nontrivial dependency of the sensor sensitivity on the frequency of the magnetic field to be measured and can effectively decrease the sensor bandwidth by up to an order of magnitude. We show that the contribution of the modulation from the nonlinearity of the magnetostrictive strain to the sensor sensitivity can be changed by applying a magnetic bias field, offering an additional dimension to the design of ME sensors, especially for potential applications in the unshielded environment.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
14 pages, 3 figures
Dissipative anomalies of stresses in soft amorphous solids: footprints of density singularities
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
In soft amorphous solids, localized irreversible (plastic) stress dissipation occurs as a response to external forcings. A crucial question is whether we can identify structural properties linked to a region's propensity to undergo a plastic stress drop when thermal effects are negligible. To address this question, I follow a theoretical framework provided by Onsager's ideal turbulence theory, representing a non-perturbative application of the renormalization group scale-invariance principle. First, I analyze the zero temperature limit for the fine-grained balance equation for the stress tensor corresponding to instanton realizations. I show that irreversible stress drops can occur if the density gradients diverge. I then derive a balance relation for the coarse-grained instantaneous stress tensor with arbitrary regularization scale \(\ell\). From the latter, I obtain an expression for the local inter-scale stress flux in terms of moments of the density increments. By assuming that the density field is Besov regular, I determine the scaling of the stress flux with \(\ell\). From this scaling, I show that distributional solutions of the noiseless Dean (NDE) equation can sustain stress dissipation due to a non-equilibrium inter-scale stress flux if the scaling exponents of the density structure functions are below a critical threshold. The athermal limit of fine-grained and coarse-grained descriptions must describe the same phenomenology, the existence of stress dissipation must be independent of any regularization of the dynamics. Using this principle, I analyze the limit \(\ell\rightarrow 0\) and argue that flow realizations of athermal disordered systems correspond to ultraviolet fixed-point solutions of the coarse-grained NDE equations with sufficiently low Besov regularity.
Soft Condensed Matter (cond-mat.soft), Mathematical Physics (math-ph)
Spin-to-charge conversion at KTaO3(111) interfaces
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Athby H. Al-Tawhid, Rui Sun, Andrew H. Comstock, Divine P. Kumah, Dali Sun, Kaveh Ahadi
Rashba spin-orbit coupling locks the spin with momentum of charge carriers at the broken inversion interfaces, which could generate a large spin galvanic response. Here, we demonstrate spin-to-charge conversion (inverse Rashba-Edelstein effect) in KTaO3(111) two-dimensional electron systems. We explain the results in the context of electronic structure, orbital character, and spin texture at the KTaO3(111) interfaces. We also show that the angle dependence of the spin-to-charge conversion on in-plane magnetic field exhibits a nontrivial behavior which matches the symmetry of the Fermi states. Results point to opportunities to use spin-to-charge conversion as a tool to investigate the electronic structure and spin texture.
Materials Science (cond-mat.mtrl-sci)
Chiral ground states in a nematic liquid crystal confined to a cylinder with homeotropic anchoring
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
The singular potential method in the Q tensor order parameter representation is used to determine the ground state configuration of an elastically anisotropic nematic liquid crystal when confined to a cylindrical geometry with homeotropic anchoring. Ground states of broken chiral symmetry are found for sufficiently small values of the twist elastic constant relative to bend and splay constants. For small cylinder radius, twisted configurations, which feature two disclinations lines that wind around the long axis of the cylinder, are generally found to minimize the free energy of the nematic. For larger radii, ground state configurations are (non singular) escaped configuration. Twisted and untwisted escaped configurations are almost degenerate in energy in this region. This near degeneracy is broken when splay-bend contrast is allowed.
Soft Condensed Matter (cond-mat.soft)
11 pages, 10 figures
Soft phonon and the central peak at the cubic-to-tetragonal phase transition in SrTiO\(_3\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-24 20:00 EST
Avishek Maity, Klaus Habicht, Michael Merz, Ayman H. Said, Christo Guguschev, Danny Kojda, Britta Ryll, Jan-Ekkehard Hoffmann, Andrea Dittmar, Thomas Keller, Frank Weber
The continuous displacive phase transition in SrTiO\(_3\) near \(T_c \approx 105\) K features a central elastic peak in neutron scattering investigations at temperatures above \(T_c\), i.e., before the corresponding soft phonon mode is overdamped upon cooling. The origin of this central peak is still not understood. Here, we report an inelastic x-ray scattering investigation of the cubic-to-tetragonal phase transition in SrTiO\(_3\). We compare quantitatively measurements of the soft phonon mode on two differently grown samples and discuss the findings regarding results from thermodynamic probes such as specific heat and thermal conductivity. Furthermore, we use inelastic x-ray scattering to perform elastic scans with both high momentum- and milli-electronvolt energy-resolution and, thus, be able to separate elastic intensities of the central peak from low-energy quasielastic phonon scattering. Our results indicate that the evolution of the soft mode is similar in both samples though the intensities of the central peak differ by a factor of four. Measurements revealing anisotropic correlation lengths on cooling towards \(T_c\), indicate that local properties of the crystals to which collective lattice excitations are insensitive are likely at the origin of the central elastic line in SrTiO\(_3\).
Strongly Correlated Electrons (cond-mat.str-el)
Manuscript contains 8 pages, 4 figures. Supplementary information contains 26 pages, 13 figures
Constructing a variational ground state of matter fermions coupled to a vison pair in Kitaev's honeycomb model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-24 20:00 EST
We develop a new method to construct simple and explicit variational approximations for the ground state of Kitaev's honeycomb model with a non-trivial Z2 flux configuration consisting of a pair of visons on neighbouring plaquettes. The method consists of retaining only the largest singular values of the generator of the transformation between the vison-pair and flux-free ground states. We compare physical quantities calculated using the approximate state to those obtained by extrapolating results of exact diagonalisation of finite lattices, finding them to be in very good agreement. We discuss ways to extend the method to more complicated flux configurations.
Strongly Correlated Electrons (cond-mat.str-el)
10 pages, 3 figures
Stable Neel-Twisted Skyrmion Bags in a van der Waals Magnet Fe3-xGaTe2 at Room Temperature
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Jialiang Jiang, Yaodong Wu, Lingyao Kong, Yongsen Zhang, Sheng Qiu, Huanhuan Zhang, Yajiao Ke, Shouguo Wang, Mingliang Tian, Jin Tang
Magnetic skyrmion bags with diverse topological charges Q, offer prospects for future spintronic devices based on freedom of Q. While their emergence in van der Waals magnets holds the potential in developing Q-based 2D topological spintronics. However, previous room-temperature skyrmion bags necessitate special anisotropy engineering through disorder Fe intercalation, and the stable phase diagram for skyrmion bags across room temperature regions is lacking. Here, we demonstrate the observation and electrical manipulation of room temperature skyrmion bags in Fe3-xGaTe2 without specially designed Fe intercalation. Combining the pulsed currents with the assistance of magnetic fields, skyrmion bags with various topological charges are generated and annihilated. Especially double nested skyrmion bags are also discovered at room temperature. The stable temperature-field diagram of skyrmion bags has been established. We also demonstrate the electrical-controlled topological phase transformations of skyrmion bags. Our results will provide novel insights for the design of 2D skyrmion-based high-performance devices.
Materials Science (cond-mat.mtrl-sci)
Published in Nano Letters DOI: https://doi.org/10.1021/acs.nanolett.4c06281
Analytical solution for the relaxed atomic configuration of twisted bilayer graphene including heterostrain
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-24 20:00 EST
Continuum atomic relaxation models for twisted bilayer graphene involve minimization of the sum of intralayer elastic energy and interlayer adhesion energy. The elastic energy favors a rigid twist i.e. no distortion in the twisted honeycomb lattices, while the adhesion energy favors Bernal stacking and breaking the relaxation into triangular AB and BA stacked domains. We compare the results of two relaxation models with the published Bragg interferometry data, finding good agreement with one of the models. We then provide a method for finding a highly accurate approximation to the solution of this model which holds above the twist angle of \(\approx0.7^\circ\) and thus covers the first magic angle. We find closed form expressions in the absence, as well as in the presence, of external heterostrain. These expressions are not written as a Taylor series in the ratio of adhesion and elastic energy, because, as we show, the radius of convergence of such a series is too small to access the first magic angle.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
14 pages, 7 figures, and 8 pages appendix
Quantum critical electro-optic and piezo-electric nonlinearities
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Christopher P. Anderson, Giovanni Scuri, Aaron Chan, Sungjun Eun, Alexander D. White, Geun Ho Ahn, Christine Jilly, Amir Safavi-Naeini, Kasper Van Gasse, Lu Li, Jelena Vučković
Electro-optics, the tuning of optical properties of materials with electric fields, is key to a multitude of quantum and classical photonics applications. However, a major obstacle preventing many emerging use cases is inefficient modulation in cryogenic environments, as traditional tuning mechanisms degrade at low temperatures. Guided by the connection between phase transitions and nonlinearity, we identify the quantum paraelectric perovskite SrTiO\(_3\) (STO) as the strongest cryogenic electro-optic photonic material. As a result of the unique quantum paraelectric phase of STO, we demonstrate a dynamically tunable linear Pockels coefficient (\(r_{33}\)) exceeding 500 pm/V at \(T=5\) K, and study its full temperature and bias dependence. We also measure an enhanced piezo-electric coefficient (\(d_{33}\)) above 90 pC/N. Both of these coefficients exceed all previously reported values for cryogenic materials, including lithium niobate (\(r_{33}\approx24\) pm/V) and barium titanate (\(r_{42}\approx170\) pm/V). Furthermore, by tuning STO towards with oxygen isotope substitution we more than double the optical and piezo-electric nonlinearities, demonstrating a linear Pockels coefficient above 1100 pm/V. Our results probe the link between quantum phase transitions, dielectric susceptibility, and optical nonlinearities, unlocking opportunities in cryogenic optical and mechanical systems, and provide a framework for discovering new nonlinear materials.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Optics (physics.optics), Quantum Physics (quant-ph)
Quantum Emitters in Flux Grown hBN
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Evan Williams, Angus Gale, Jake Horder, Dominic Scognamiglio, Milos Toth, Igor Aharonovich
Hexagonal boron nitride (hBN) is an emerging material for use in quantum technologies, hosting bright and stable single photon emitters (SPEs). The B-center is one promising SPE in hBN, due to the near-deterministic creation methods and regular emission wavelength. However, incorporation of B-centers in high-quality crystals remains challenging, typically relying on additional post-growth methods to increase creation efficiency. Here, we have demonstrated controlled carbon doping of hBN during growth, using a metal flux based method to increase the efficiency of B-center creation. Importantly, single B-centers with \(g^{(2)}(0) < 0.5\) were able to be generated in the as-grown hBN when carbon additions during growth exceeded 2.5 wt.% C. Resonant excitation measurements revealed linewidths of 3.5 GHz with only moderate spectral diffusion present, demonstrating the applicability of the as-grown hBN as a host for high quality B-centers.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Optics (physics.optics)
Decoding lithium's subtle phase stability with a machine learning force field
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Understanding the phase stability of elemental lithium (Li) is crucial for optimizing its performance in lithium-metal battery anodes, yet this seemingly simple metal exhibits complex polymorphism that requires proper accounting for quantum and anharmonic effects to capture the subtleties in its flat energy landscape. Here we address this challenge by developing an accurate graph neural network-based machine learning force field and performing efficient self-consistent phonon calculations for bcc-, fcc-, and 9R-Li under near-ambient conditions, incorporating quantum, phonon renormalization and thermal expansion effects. Our results reveal the important role of anharmonicity in determining Li's thermodynamic properties. The free energy differences between these phases, particularly fcc- and 9R-Li are found to be only a few meV/atom, explaining the experimental challenges in obtaining phase-pure samples and suggesting a propensity for stacking faults and related defect formation. fcc-Li is confirmed as the ground state at zero temperature and pressure, and the predicted bcc-fcc phase boundary qualitatively matches experimental phase transition lines, despite overestimation of the transition temperature and pressure slope. These findings provide crucial insights into Li's complex polymorphism and establish an effective computational approach for large-scale atomistic simulations of Li in more realistic settings for practical energy storage applications.
Materials Science (cond-mat.mtrl-sci)
Single monolayer ferromagnetic perovskite SrRuO3 with high conductivity and strong ferromagnetism
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Yuki K. Wakabayashi, Masaki Kobayashi, Yoshiharu Krockenberger, Takahito Takeda, Kohei Yamagami, Hideki Yamamoto, Yoshitaka Taniyasu
Achieving robust ferromagnetism and high conductivity in atomically thin oxide materials is critical for advancing spintronic technologies. Here, we report the growth of a highly conductive and ferromagnetic single monolayer SrRuO3 having a high Curie temperature of 154 K on DyScO3 110 substrates. The SrTiO3 capping layer effectively suppresses surface reactions, which typically hinder ferromagnetism in atomically thin films. X ray absorption spectroscopy and X ray magnetic circular dichroism measurements revealed strong orbital hybridization between Ru 4d and O 2p orbitals in the SRO monolayer, which contributes to enhancement of the conductivity and ferromagnetic ordering of both the Ru 4d and O 2p orbitals. The resistivity of the single monolayer SrRuO3 on the better lattice matched DyScO3 substrate is approximately one-third of that of previously reported single monolayer SrRuO3 grown on an SrTiO3 substrate. This study highlights the potential of monolayer SrRuO3 as a platform for two dimensional magnetic oxide systems, offering new opportunities for the eploration of spintronic devices and quantum transport phenomena.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Self-assembly of anisotropic particles on curved surfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
Gautam Bordia, Thomas P. Russell, Ahmad K. Omar
The surface curvature of membranes, interfaces, and substrates plays a crucial role in shaping the self-assembly of particles adsorbed on these surfaces. However, little is known about the interplay between particle anisotropy and surface curvature and how they couple to alter the free energy landscape of particle assemblies. Using molecular dynamics simulations, we investigate the effect of prescribed curvatures on a quasi-2D assembly of anisotropic patchy particles. By varying curvature and surface coverage, we uncover a rich geometric phase diagram, with curvature inducing ordered structures entirely absent on planar surfaces. Large spatial domains of ordered structures can contain hidden microdomains of orientational textures imprinted by the surface on the assembly. The dynamical landscape is also reshaped by surface curvature, with a glass state emerging at modest densities and high curvature. Our findings show that the coupling between surface curvature and particle geometry opens a new space of morphologies and structures that can be exploited for material design.
Soft Condensed Matter (cond-mat.soft)
Turing patterns on polymerized membranes: a coarse-grained lattice modelling with internal degree of freedom for polymer direction
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
F.Kato, H.Koibuchi, E.Bretin, C.Carvalho, R.Denis, S.Masnou, M. Nakayama, S.Tasaki, T.Uchimoto
We numerically study Turing patterns (TPs) on two-dimensional surfaces with a square boundary in \({\bf R}^3\) using a surface model for polymerized membranes. The variables used to describe the membranes correspond to two distinct degrees of freedom: an internal degree of freedom for the polymer directions in addition to the positional degree of freedom. This generalised surface model enables us to identify a non-trivial interference between the TP system and the membranes. To this end, we employ a hybrid numerical technique, utilising Monte Carlo updates for membrane configurations and discrete time iterations for the FitzHugh-Nagumo type Turing equation. The simulation results clearly show that anisotropies in the mechanical deformation properties, particularly the easy axes associated with the stretching and bending of the membranes, determine the direction of the TPs to be perpendicular or parallel to the easy axes. Additionally, by calculating the dependence of the maximum entropy on the internal degree of freedom, we can obtain information on the relaxation with respect to the polymer structure. This crucial information serves to remind us that non-equilibrium configurations can be captured within the canonical Monte Carlo simulations.
Soft Condensed Matter (cond-mat.soft), Pattern Formation and Solitons (nlin.PS)
21 pages, 16 figures, supplementary materials (1),(2) and (3)
Gate tunable Dirac mass and Berry phase in Trilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-24 20:00 EST
Harsimran Kaur Mann, Simrandeep Kaur, Safil Mullick, Priya Tiwari, Kenji Watanabe, Takashi Taniguchi, Aveek Bid
In-situ control over band mass inversion is crucial for developing materials with topologically protected edge modes. In this Letter, we report the direct observation of displacement field \(D\) control of band mass and Berry phase in Bernal stacked trilayer graphene (TLG) in the region where trigonal warping distorts the quadratic band into off-center Dirac points, referred to as `Dirac Gullies.' Using Shubnikov-de-Haas (SdH) oscillations, we map the Fermi surface contours of the Dirac gullies and the \(D\)-dependent band structure. With increasing \(D\)-field, the Berry phase undergoes multiple transitions from \(\Phi_B=2\pi\) \(\rightarrow\) \(\pi\) \(\rightarrow\) \(2\pi\) as \(D\) is varied. Concurrently, measurement of the effective mass reveals a series of transitions between massless and massive bands, signaling the closure and reopening (accompanied by a possible band inversion) of the band gap at a critical value of \(D\). Interestingly, the expected Dirac-like behavior of the Dirac gullies (\(\Phi_B=\pi\)) persists only over a narrow range of \(D\). Our study directly confirms recent predictions of $ D$-field-induced band inversion in the low-energy regions of TLG. It is a significant step towards achieving control over pure valley transport in multilayer graphene.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
16 pages, comments and suggestions most welcome
Mass enhancement and metal-nonmetal transition driven by d-f hybridization in perovskites La1-xPrxCuO3
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-24 20:00 EST
H. Takahashi, M. Ito, J. Fujioka, M. Ochi, S. Sakai, R. Arita, H. Sagayama, Y. Yamasaki, S. Ishiwata
We report the large electron-mass enhancement and the metal to nonmetal transition upon the Pr doping in perovskite-type La1-xPrxCuO3. With increasing the Pr content x around 0.6, the LaCuO3-type three-dimensional structure with trivalent Cu ions changes to the quasi-one-dimensional structure with nearly divalent Cu ions, which accompanies significant changes in the electronic properties. Based on the resistivity, optical conductivity, specific heat measurements and the first-principles calculations, we discuss the formation of a nearly localized nonmetallic state stabilized by the hybridization between Cu 3d, O 2p, and Pr 4f orbitals in the quasi-one-dimensional lattice. The present perovskite-type cuprates offer a unique opportunity to explore novel quantum phases of correlated electrons in low-dimensional lattice, where the spin/charge/orbital degrees of freedom of A- and B-site ions are entangled.
Strongly Correlated Electrons (cond-mat.str-el)
5 pages,4 figures
RFSoC-based radio-frequency reflectometry in gate-defined bilayer graphene quantum devices
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-24 20:00 EST
Motoya Shinozaki, Tomoya Johmen, Aruto Hosaka, Takumi Seo, Shunsuke Yashima, Akitomi Shirachi, Kosuke Noro, Shoichi Sato, Takashi Kumasaka, Tsuyoshi Yoshida, Tomohiro Otsuka
Quantum computers require both scalability and high performance for practical applications. While semiconductor quantum dots are promising candidates for quantum bits, the complexity of measurement setups poses an important challenge for scaling up these devices. Here, radio-frequency system-on-chip (RFSoC) technology is exepcted for a promising approach that combines scalability with flexibility. In this paper, we demonstrate RF reflectometry in gate-defined bilayer graphene quantum devices using RFSoC-based measurement architecture. By controlling the confinement strength through gate voltages, we achieve both Fabry-Pérot interferometer and quantum dot operations in a single device. Although impedance matching conditions currently limit the measurement sensitivity, we identify pathways for optimization through tunnel barrier engineering and resonator design. These results represent a step toward integrating high-bandwidth measurements with scalable quantum devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 4 figures
Looking at bare transport coefficients in fluctuating hydrodynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-24 20:00 EST
Hiroyoshi Nakano, Yuki Minami, Keiji Saito
Hydrodynamics at the macroscopic scale, composed of a vast ensemble of microscopic particles, is described by the Navier-Stokes equation. However, at the mesoscopic scale, bridging the microscopic and macroscopic domains, fluctuations become significant, necessitating the framework of fluctuating hydrodynamics for accurate descriptions. A central feature of this framework is the appearance of noises and transport coefficients, referred to as bare transport coefficients. These coefficients, generally different from the macroscopic transport coefficients of the deterministic Navier-Stokes equation, are challenging to measure directly because macroscopic measurements typically yield the latter coefficients. This paper addresses the questions of how bare transport coefficients manifest in measurable physical quantities and how practical methodologies can be developed for their determination. As a prototype example, we examine the shear viscosity of two-dimensional dense fluids. The numerical simulations of the fluctuating hydrodynamic equations reveal that near solid walls, where hydrodynamic fluctuations are significantly suppressed, the bare shear viscosity governs the fluid dynamics. The theoretical calculations, based on perturbation expansion of the fluctuating hydrodynamic equations, confirm this suppression of hydrodynamic fluctuations at walls and yield analytical expressions for the observed shear viscosity. Based on this finding, we develop a methodology to accurately determine the bare shear viscosity using a controlled shear flow. Furthermore, we provide detailed numerical investigations of the role of an ultraviolet cutoff length in fluctuating hydrodynamics. These establish that the lower bound of the ultraviolet cutoff length is on the order of atomic diameter and highlight that bare viscosity is determined solely by microscopic details below this scale.
Statistical Mechanics (cond-mat.stat-mech), Fluid Dynamics (physics.flu-dyn)
11+16 pages, 5+8 figures
Anisotropic Exchange Spin Model to Investigate the Curie Temperature Dispersion of Finite-Size L10-FePt Magnetic Nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Kohei Ochiai, Tomoyuki Tsuyama, Sumera Shimizu, Lei Zhang, Jin Watanabe, Fumito Kudo, Jian-Gang Zhu, Yoshishige Okuno
We developed an anisotropic spin model that accounts for magnetic anisotropy and evaluated the Curie temperature (Tc) dispersion due to finite size effects in L10-FePt nanoparticles. In heat-assisted magnetic recording (HAMR) media, a next-generation magnetic recording technology, high-density recording is achieved by locally heating L10-FePt nanoparticles near their Tc and rapidly cooling them. However, variations in Tc caused by differences in particle size and shape can compromise recording stability and areal density capacity, making the control of Tc dispersion critical. In this study, we constructed atomistic LLG models to explicitly incorporate the spin exchange anisotropy of L10-FePt, based on parameters determined by first-principles calculations. Using this model, we evaluated the impact of particle size on Tc dispersion. As a result, (1) the Tc dispersion critical to the performance of HAMR can be reproduced, whereas it was previously underestimated by isotropic models and (2) approximately 70% of the experimentally observed Tc dispersion can be attributed to particle size effects. This research highlights the role of exchange anisotropy in amplifying finite-size effects and underscores the importance of size control in HAMR media.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 6 figures
Ultra-Stable Ferrimagnetic Second-Order Topological Insulator in 2D Metal-Organic Framework
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Meijun Wang, Yong-An Zhong, Lei Jin, Ying Liu, Xuefang Dai, Guodong Liu, Xiaoming Zhang
Two-dimensional (2D) magnetic second-order topological insulators (SOTIs) exhibit distinct topological phases characterized by spin-polarized zero-dimensional (0D) corner states, which have garnered significant interest. However, 2D ferrimagnetic (FiM) SOTIs, particularly those that simultaneously exhibit ultra-stable corner states, are still lacking. Here, based on first-principles calculations and theoretical analysis, we reveal such SOTI state in a 2D metal-organic framework (MOF) material, Cr(pyz)2 (pyz = pyrazine). This material exhibits FiM ground state with an easy axis aligned along [001] direction. It hosts a nontrivial real Chern number in the spin-up channel, enabled by PT symmetry, with 0D corner states observable in disk. In contrast, the spin-down channel exhibits a trivial gapped bulk state. Notably, the topological corner states in monolayer Cr(pyz)2 show high robustness, even if the symmetries are broken by introducing defects, the corner states persist. We also considered other external perturbations, including uniaxial/biaxial strain, ligand rotation, and electric fields, the corner states still remain stable. Even more, the energy positions of the corner states are also nearly unchanged. This work is the first to identify ultra-stable FiM SOTI state in the MOF system, and provide an ideal platform for future experimental investigations and applications in spintronic devices.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Self-assembly of Dipolar Crystals from Magnetic Colloids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
Anuj Kumar Singh, Sanjay Puri, Varsha Banerjee
We study the self-assembly of magnetic colloids using the Stockmayer (SM) model characterized by short-range Lennard-Jones interactions and long-range dipole-dipole interactions. Using molecular dynamics simulations, we design cooling protocols that yield perfectly assembled single-domain magnetic crystals. We identify cooling rates at which the system transforms from an amorphous glass to a crystal, where magnetic ordering promotes crystalline order. Remarkably, we observe that the latter develops via a spontaneous transition rather than through the traditional nucleation and growth mechanism. For a weakly dipolar fluid (\(\mu=1\)), this self-assembly results in a face-centered cubic (FCC) colloidal crystal with dipole moments chained along the (111) direction. For fluids with higher dipole moment (\(\mu = 2.5\)), the crystal structure shifts towards a body-centered orthorhombic (BCO) arrangement due to the compression of chains from strong dipolar attractions. These results provide valuable insights into the mechanisms driving crystallization in magnetic fluids, opening new avenues for understanding the formation of magnetically responsive colloidal magnetic crystals with promising applications.
Soft Condensed Matter (cond-mat.soft)
Fermionic free energies from path integral Monte Carlo simulations of fictitious identical particles
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-24 20:00 EST
Tobias Dornheim, Zhandos Moldabekov, Sebastian Schwalbe, Panagiotis Tolias, Jan Vorberger
We combine the recent \(\eta-\)ensemble path integral Monte Carlo (PIMC) approach to the free energy [T.~Dornheim , , L041114 (2025)] with a recent fictitious partition function technique based on inserting a continuous variable that interpolates between the bosonic and fermionic limits [Xiong and Xiong, ~, 094112 (2022)] to deal with the fermion sign problem. As a practical example, we apply our set-up to the warm dense uniform electron gas over a broad range of densities and temperatures. We obtain accurate results for the exchange--correlation free energy down to half the Fermi temperature, and find excellent agreement with the state-of-the-art parametrization by Groth ~[~, 135001 (2017)]. Our work opens up new avenues for the future study of a host of interacting Fermi-systems, including warm dense matter, ultracold atoms, and electrons in quantum dots.
Quantum Gases (cond-mat.quant-gas), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
Sol-gel transition in heteroassociative RNA-protein solutions: A quantitative comparison of coarse-grained simulations and the Semenov-Rubinstein theory
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
Xinxiang Chen, Jude Ann Vishnu, Pol Besenius, Julian König, Friederike Schmid
Protein RNA-binding domains selectively interact with specific RNA sites, a key interaction that determines the emergent cooperative behaviors in RNA-protein mixtures. Through molecular dynamics simulations, we investigate the impact of the specific binding interactions on the phase transitions of an examplary RNA-protein system and compare it with predictions of the Semenov-Rubinstein theory of associative polymers. Our findings reveal a sol-gel (percolation) transition without phase separation, characterized by double reentrant behavior as the RNA or protein concentration increases. We highlight the crucial role of bridge formations in driving these transitions, particularly when binding sites are saturated. The theory quantitatively predicts the binding numbers at equilibrium in the semidilute regime, but it significantly overestimates the size of the concentration range where percolation is observed. This can partly be traced back to the fact that the mean-field assumption in the theory is not valid in the dilute regime, and that the theory neglects the existence of cycles in the connectivity graph of the percolating cluster at the sol-gel transition. Our study enriches the understanding of RNA-protein phase behaviors, providing valuable insights for the interpretation of experimental observations.
Soft Condensed Matter (cond-mat.soft)
Collective behaviors of self-propelled particles with tunable alignment angles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
We present a novel aligning active matter model by extending the nematic alignment rule in self-propelled rods to tunable alignment angles, as represented by collision of cone-shaped particles. Non-vanishing alignment angles introduce frustration in the many-body interactions, and we investigate its effect on the collective behavior of the system. Through numerical simulations of an agent-based microscopic model, we found that the system exhibits distinct phenomenology compared to the original self-propelled rods. In particular, anti-parallel bands are observed in an intermediate parameter range. The linear stability analysis of the continuum description derived from the Boltzmann approach demonstrates qualitative consistency with the microscopic model, while frustration due to many-body interactions in the latter destabilizes homogeneous nematic order over a wide range of the alignment angle.
Soft Condensed Matter (cond-mat.soft), Adaptation and Self-Organizing Systems (nlin.AO)
6 pages, 5 figures
Two-dimensional fully-compensated Ferrimagnetism
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Yichen Liu, San-Dong Guo, Yongpan Li, Cheng-Cheng Liu
Antiferromagnetic spintronics has long been a subject of intense research interest, and the recent introduction of altermagnetism has further ignited enthusiasm in the field. However, fully-compensated ferrimagnetism, which exhibits band spin splitting but zero net magnetization, has yet to receive enough attention. Since the experimental preparation of two-dimensional (2D) magnetic van der Waals (vdW) materials in 2017, 2D magnetic materials, thanks to their super tunability, have quickly become an important playground for spintronics. Here, we extend the concept of fully-compensated ferrimagnetism (fFIM) to two dimensions and propose 2D fFIM, demonstrate its stability and ease of manipulation, and present three feasible realization schemes with respective exemplary candidate materials. A simple model for 2D fully-compensated ferrimagnets (fFIMs) is developed. Further investigation of 2D fFIMs' physical properties reveals that they not only exhibit significant magneto-optical response but also show fully spin-polarized currents and the anomalous Hall effect in the half-metallic states, displaying characteristics previously almost exclusive to ferromagnetic materials, greatly broadening the research and application prospects of spintronic materials.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Phys. Rev. Lett. (2025); 7-page text + 7-page Supplemental Material
Electron-phonon interactions and tensor analysis in topological insulator bismuth telluride using angle resolved polarized Raman spectroscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Aditya Singh, Anna Elsukova, Divya Rawat, Saswata Talukdar, Surajit Saha, Arnaud le Febvrier, Per O. Å. Persson, Per Eklund, Ajay Soni
We report on the angle-resolved polarized Raman spectroscopy and estimation of the Raman tensor elements using both classical and quantum treatments to analyse the polarized Raman spectra of single crystal Bismuth Telluride. The observed polar patterns and systematic variations in the relative intensities of four characteristic Raman active modes indicate a higher differential polarizability along the c-axis, accompanied by anisotropic photon-phonon interactions. This interplay of electron-photon-phonon interactions is crucial for understanding the lattice dynamics of Bismuth Telluride, which underpin its thermoelectric performance and topological properties.
Materials Science (cond-mat.mtrl-sci)
15 Pages, 4 Figures
(111) Facet-engineered SnO2 as Electron Transport Layer for Efficient and Stable Triple-Cation Perovskite Solar Cells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Keshav Kumar Sharma, Rohit, Sochannao Machinao, Ramesh Karuppannan
We report the (111) facet-engineered cubic phase SnO2 (C-SnO2) as a novel electron transport layer (ETL) for triple-cation mixed-halide Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3 perovskite solar cells (PSCs). The C-SnO2 layer was prepared via a normal sol-gel process followed by the spin-coating technique. The (111) facet C-SnO2 layer provides a larger surface contact area with an adjacent perovskite layer, enhancing charge transfer dynamics at the interface. In addition, the well-matched overlapping band structures improve the charge extraction efficiency between the two layers. Using (111) facet C-SnO2 as ETLs, we obtain PSCs with a higher power conversion efficiency of 20.34% (0.09 cm2) than those employing tetragonal phase SnO2 ETL. The PSCs with C-SnO2 ETL retain over 81% of their initial efficiency even after 480 h. This work concludes with a brief discussion on recombination and charge transport mechanisms, providing ways to optimize C-SnO2 ETL to improve the PSCs' performance and stability.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
18 pages, 9 figures
Nanoindentation responses of Fe-Cr alloys from room temperature to 600 °C
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
L. Kurpaska, M. Clozel, J. H. OConnell, I. Jozwik, E. Wyszkowska, W. Y. Huo, W. Chrominski, D. Kalita, S. T. Nori, F. Fang, J. Jagielski, J. H. Neethling
In this work, the evolution of nanomechanical properties was studied systematically as a function of temperature, chemical, and microstructural complexity of different Fe-based alloys. Experiments were performed at different temperatures (room temperature, 200 C, 400 C, 600 C) using the nanoindentation technique on low activation Fe9Cr-1WVTa (Eurofer97), model Fe-9Cr-NiSiP, Fe-9Cr alloys, and pure iron samples, followed by microstructural observations. The results show varying softening and hardening effects depending on the experimental temperature, demonstrating Portevin-Le-Chatelier effect, i.e., dynamic strain aging phenomenon in model alloys. Sources of the dynamic strain aging instabilities were traced back to the interaction between dislocations and alloying elements such as interstitial carbon and substitutional chromium. The materials undergo dynamic recovery and recrystallization below the regions of high-temperature indentation depending on the pre-indentation dislocation density and the alloy composition. Our findings help in the understanding of the structure and mechanical property relationship in complex Eurofer97 alloy at high-temperatures for potential nuclear applications as structural materials.
Materials Science (cond-mat.mtrl-sci)
Vertex correction for the linear and nonlinear optical responses in superconductors: multiband effect and topological superconductivity
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-24 20:00 EST
Intensive research has revealed intriguing optical responses in topological materials. This paper focuses on the optical responses in \(s\)-wave superconductors with a Rashba spin-orbit coupling and a magnetic field, one of the platforms of topological superconductivity. On the one hand, to satisfy some conservation laws in superconducting responses, it is essential to take into account collective excitation modes. On the other hand, the optical response is a promising phenomenon for detecting hidden collective modes in superconductors. In this paper, we investigate the effect of collective excitation modes on the linear and second-order optical responses based on the self-consistent response approximation, which is formulated using the Kadanoff-Baym method. Our main results reveal that the Higgs mode enhances the optical responses when the Fermi level is close to the Dirac point. The enhancement is due to the multiband effects characterized by interband pairing. We also demonstrate the sign reversal of the photocurrent conductivity around the topological transition with increasing the Zeeman field. This finding supports the prediction in our previous work without considering collective excitation modes [H. Tanaka, et al., Phys. Rev. B 110, 014520 (2024)]. The sign reversal phenomenon is attributed to the magnetic injection current modified by the Higgs mode, and is proposed for a bulk probe of topological superconductors. We also discuss the interplay of quantum geometry and collective modes.
Superconductivity (cond-mat.supr-con)
37 pages, 13figures
Developing an unfolding-incorporated coarse-grained polymer model for fibrinogen to study the mechanical behaviour
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
Vivek Sharma, Poulomi Sadhukhan
Fibrinogen is a protein found in blood that forms Fibrin polymer network to build a clot during wound healing process when there is a cut in the blood vessel. The fibrin fiber is highly stretchable and shows a complex mechanical properties. The fibrin monomer, Fibrinogen, has a very complex structure which is responsible for its unusual elastic behaviour. In this work, we focus on mechanism of unfolding of D-domain of Fibrinogen, and study its effect in the mechanical behaviour. We develop a coarse-grained (CG) bead-spring model for Fibrinogen which captures the unfolding of folded D-domains along with other necessary structural properties which affect the mechanical behaviour. The results from our unfolding-incorporated coarse-grained polymer (UCGP) model matches with the experimental results. This model has capacity to serve as the minimal unit to build a large-scale hierarchical structure of fibrin fiber and network to possibly unfold the mystery of fibrin's unusual elastic behaviour. This model can also be used for other polymers having folded domains or sacrificial bonds.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
8 pages, 4 figures
Superconducting phenomena in systems with unconventional magnets
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-24 20:00 EST
Yuri Fukaya, Bo Lu, Keiji Yada, Yukio Tanaka, Jorge Cayao
In this work we review the recent advances on superconducting phenomena in junctions formed by superconductors and unconventional magnets. Conventional magnets, such as ferromagnets and antiferromagnets, are characterized by broken time-reversal symmetry but only ferromagnets produce a finite net magnetization due to parallel spin alignment and spin-split bands in momentum. Very recently, a new type of magnets have been reported and here we refer to them as because they exhibit special properties of both ferromagnets and antiferromagnets: they exhibit zero net magnetization (like antiferromagnets) and a nonrelativistic spin splitting of energy bands (like ferromagnets), both leading to anisotropic spin-polarized Fermi surfaces. An interesting property of unconventional magnets is that their magnetic order can be even or odd with respect to momentum, where and are the most representative examples. In this regard, \(d\)-wave altermagnetism and \(p\)-wave magnets are seen as counterparts in magnetism of the unconventional \(d\)-wave and \(p\)-wave superconducting states, respectively. While the impact of conventional magnetism on superconductivity has been largely studied, the combination of unconventional magnets and superconductivity has only lately attracted considerably attention. This work provides a comprehensive review of the recent progress on the interplay between superconductivity and unconventional magnets. In particular, we focus on the fundamental emerging superconducting phenomena and also discuss the potential implications towards quantum applications.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
54 pages, 23 figures. Invited topical review. Comments are welcome
Evidence for magnetic crystallization waves at the surface of \(^3\)He crystal
New Submission | Other Condensed Matter (cond-mat.other) | 2025-02-24 20:00 EST
Igor Todoshchenko, Alexander Savin, Pertti J. Hakonen
Ultralow temperature crystals of the helium isotopes \(^3\)He and \(^4\)He are intriguing quantum systems. Deciphering the complex features of these unusual materials has been made possible in large part by Alexander Andreev's groundbreaking research. In 1978, Andreev and Alexander Parshin predicted the existence of melting/freezing waves at the surface of a solid \(^4\)He crystal, which was subsequently promptly detected. Successively, for the fermionic \(^3\)He superfluid/solid interface, even more intricate crystallization waves were anticipated, although they have not been observed experimentally so far. In this work, we provide preliminary results on \(^3\)He crystals at the temperature \(T = 0.41\);mK, supporting the existence of spin supercurrents in the melting/freezing waves on the crystal surface below the antiferromagnetic ordering temperature \(T_N= 0.93\);mK, as predicted by Andreev. The spin currents that accompany such a melting-freezing wave make it a unique object, in which the inertial mass is distinctly different from the gravitational mass.
Other Condensed Matter (cond-mat.other)
A New Type of MPd5 Kagome Superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-24 20:00 EST
Dan Li, Zhengxuan Wang, Panshi Jing, Mehrdad Shiri, Kun Wang, Chunlan Ma, Shijing Gong, Chuanxi Zhao, Tianxing Wang, Xiao Dong, Lin Zhuang, Wuming Liu, Yipeng An
Kagome materials, which are composed of hexagons tiled with a shared triangle, have inspired enormous interest due to their unique structures and rich physical properties, but exploring superconducting material systems with new kagome structures is still an important research direction. Here, we predict a new type of kagome superconductors, MPd5 (M is a group IIA metal element), and identify that they exhibit coexistence of superconductivity and non-trivial topological properties. We uncover their phonon-mediated superconductivity by the density functional theory for superconductors (SCDFT), predicting the superconducting transition temperatures (Tc) of 2.64, 2.03, and 1.50 K for CaPd5, SrPd5, and BaPd5, respectively, which can be effectively tuned by external pressure and electron doping. The present results also demonstrate that MPd5 have various topological properties such as, CaPd5 shows topological non-trivial intersection near the Fermi level (EF). Our results indicate that the MPd5 materials can be an emerging material platform with rich exotic physics in their kagome structures, and render themselves excellent candidates for superconducting and advanced functional materials that could be utilized in topological quantum computing and information technology.
Superconductivity (cond-mat.supr-con)
11 pages, 5 figures
Sign Changes in Heat, Spin, and Orbital Magnon Transport Coefficients in Kitaev Ferromagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-24 20:00 EST
Yannick Höpfner, Ingrid Mertig, Robin R. Neumann
Both Kitaev and Dzyaloshinskii-Moriya interactions (DMI) are known to promote intrinsic contributions to the magnon Hall effects such as the thermal Hall and the spin Nernst effects in collinear magnets. Previously, it was reported that a sign change in those transversal transport coefficients only appears in the presence of Kitaev interaction, but not for DMI, which qualitatively distinguishes both kinds of spin-anisotropic interactions in ferromagnets. Herein, we systematically study how the magnon-mediated heat, spin, and orbital transport in longitudinal and transverse geometries evolves with a continuously varying Kitaev-to-DMI ratio, but a fixed magnon band structure. We show that several transport coefficients feature temperature-driven sign changes in the presence of Kitaev interaction, which are absent for DMI. In particular, we find a sign change in longitudinal orbital transport, the magnon orbital Seebeck effect, which is absent in the transverse geometry, the magnon orbital Nernst effect. This sets the orbital transport apart from the heat and spin transport, where we only find sign changes promoted by the Kitaev interaction in transverse, but not in the longitudinal geometry.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Correlations of density and current fluctuations in single-file motion of hard spheres and in driven lattice gas with nearest-neighbor interaction
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-24 20:00 EST
Sören Schweers, Gunter M. Schütz, Philipp Maass
We analyze correlations between density fluctuations and between current fluctuations in a one-dimensional driven lattice gas with repulsive nearest-neighbor interaction and in single-file Brownian motion of hard spheres dragged across a cosine potential with constant force. By extensive kinetic Monte Carlo and Brownian dynamics simulations we show that density and current correlation functions in nonequilibrium steady states follow the scaling behavior of the Kardar-Parisi-Zhang (KPZ) universality class. In a coordinate frame comoving with the collective particle velocity, the current correlation function decays as \(\sim -t^{-4/3}\) with time \(t\). Density fluctuations spread superdiffusively as \(\sim t^{2/3}\) at long times and their spatio-temporal behavior is well described by the KPZ scaling function. In the absence of the cosine potential, the correlation functions in the system of dragged hard spheres show scaling behavior according to the Edwards-Wilkinson universality class. In the coordinate frame comoving with the mean particle velocity, they behave as in equilibrium, with current correlations decaying as \(\sim -t^{-3/2}\) and density fluctuations spreading diffusively as \(\sim t^{1/2}\).
Statistical Mechanics (cond-mat.stat-mech)
8 pages, 3 figures
String Formation and Arrested Ordering Kinetics in Nematics Induced by Polar Particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
Pawan Kumar Mishra, Partha Sarathi Mondal, Pratikshya Jena, Shradha Mishra
Our study explores the mixture of polar particles in apolar environment. We employ a coarse-grained approach to model the mixture, where polar particles are in minority. The interaction between polar and apolar components is incorporated via a coupling term in the free energy. Coupling generates local interaction in the system which results in the formation of string like structures connecting a pair of half integer topological defects. The increase in the coupling strength or the density of polar particles results in the: Sharper strings with larger probability of connecting the topological defects of same charge and the enhanced dynamics of topological defects. However, the ordering kinetics of the system shows the delayed coarsening for larger coupling or polar density. Our results can be used to develop controlled kinetics as well as to detect the impurities in liquid crystals.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Cavity QED Control of Quantum Hall Stripes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-24 20:00 EST
Lorenzo Graziotto, Josefine Enkner, Sambuddha Chattopadhyay, Jonathan B. Curtis, Ethan Koskas, Christian Reichl, Werner Wegscheider, Giacomo Scalari, Eugene Demler, Jérôme Faist
Controlling quantum phases of materials with vacuum field fluctuations in engineered cavities is a novel route towards the optical control of emergent phenomena. We demonstrate, using magnetotransport measurements of a high-mobility two-dimensional electron gas, striking cavity-induced anisotropies in the electronic transport, including the suppression of the longitudinal resistance well below the resistivity at zero magnetic field. Our cavity-induced effects occur at ultra-low temperatures (< 200 mK) when the magnetic field lies between quantized Hall plateaus. We interpret our results as arising from the stabilization of thermally-disordered quantum Hall stripes. Our work presents a clear demonstration of the cavity QED control of a correlated electronic phase.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
Main: 7 pages, 4 figures. Supplementary Material: 31 pages, 19 figures, 1 table
Thermally-induced microstructural evolution in nanoparticle-based CuO, WO\(_3\) and CuO-WO\(_3\) thin films for hydrogen gas sensing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Kalyani Shaji, Stanislav Haviar, Petr Zeman, Michal Procházka, Radomír Čerstvý, Nirmal Kumar, Jiří Čapek
This study systematically investigates the microstructural evolution of nanoparticle-based CuO, WO\(_3\), and composite 'CuO-WO\(_3\)' thin films induced by their post-deposition annealing. The films were reactively deposited using a magnetron-based gas aggregation technique, with the composite films consisting of alternating monolayers of CuO and WO\(_3\) nanoparticles. After deposition, the films were annealed in synthetic air at temperatures ranging from 200 to 400\(^\circ\)C and characterized using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Annealing of the CuO films led to the most pronounced changes associated with a gradual enhancement of crystallinity accompanied by significant particle growth with increasing annealing temperature, while the WO\(_3\) and CuO-WO\(_3\) films were more thermally stable to crystallization and particle growth. Notably, at 400\(^\circ\)C, the CuO--WO\(_3\) films crystallized into a novel \(\gamma\)-CuWO\(_4\) phase. The annealed films were further evaluated for their gas-sensing performance upon H\(_2\) exposure and the obtained results were analyzed in relation to film properties and the microstructural evolution induced by annealing.
Materials Science (cond-mat.mtrl-sci)
Lattice dynamics and spin-phonon coupling in the kagome spin ice HoAgGe
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-24 20:00 EST
Shangfei Wu, Lingxiao Zhao, Wei Song, Mingshu Tan, Feng Jin, Tianping Ying, Jia-Xin Yin, Qingming Zhang
We employ polarization-resolved Raman spectroscopy and first-principles phonon calculations to study the lattice dynamics and spin-phonon coupling in the kagome spin ice compound HoAgGe. Upon cooling, HoAgGe shows transitions from a nonmagnetic state at 300 K to a partially magnetic-ordered phase below T2 = 11.6 K, eventually reaching a fully-magnetic ordered phase below T1 = 7 K. We detect eight of ten Raman-active phonon modes at room temperature, with frequencies consistent with first-principles phonon calculations. We find that the low-energy phonon modes harden upon cooling, soften slightly below T2, and finally harden again below T1, suggesting finite spin-phonon coupling in HoAgGe. Furthermore, one high-energy mode at 185 cm-1 with E' symmetry exhibits a Fano lineshape due to electron-phonon coupling. Our Raman results establish finite spin-phonon coupling and electron-phonon coupling in the magnetic phase of HoAgGe, providing a foundation for future studies of the novel field-induced phases at low temperatures in HoAgGe.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
10 pages, 6 figures, to appear in PRB
Interaction of dopants with the I\(_3\)-type basal stacking fault in hexagonal-diamond Si
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Marc Túnica, Perpetua Wanjiru Muchiri, Alberto Zobelli, Anna Marzegalli, Emilio Scalise, Michele Amato
Recently synthesized hexagonal-diamond silicon, germanium, and silicon-germanium nanowires exhibit remarkable optical and electronic properties when compared to cubic-diamond polytypes. Because of the metastability of the hexagonal-diamond phase, I\(_3\)-type basal stacking faults are frequently observed in these materials. In the present study, we employ density functional theory calculations to investigate the interaction of extrinsic dopants (group III, IV, and V elements) with the I\(_3\)-type basal stacking fault in hexagonal-diamond silicon. Contrary to the behavior observed in cubic-diamond silicon with intrinsic stacking faults, we demonstrate that neutral and negatively charged \(p\)-type impurities exhibit a marked tendency to occupy lattice sites far from the I\(_3\)-type basal stacking fault. The interaction of acceptors with the planar defect reduces their energetic stability. However, this effect is much less pronounced for neutral or positively charged \(n\)-type dopants and isovalent impurities. The thermodynamic energy barrier to segregation for these dopants is small and may even become negative, indicating a tendency to segregate into the fault. Through a detailed analysis of structural modifications, ionization effects, and impurity-level charge density distribution, we show that the origin of this behavior can be attributed to variations in the impurity's steric effects and its wave function character. Finally, all these results are validated by considering the extreme case of an abrupt hexagonal/cubic silicon interface, where acceptor segregation from the cubic to the hexagonal region is demonstrated, confirming the behavior observed for \(p\)-type dopants near to the I\(_3\)-type defect.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Quantifying hydrogen bonding using electrically tunable nanoconfined water
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-24 20:00 EST
Ziwei Wang, Anupam Bhattacharya, Mehmet Yagmurcukardes, Vasyl Kravets, Pablo Díaz-Núñez, Ciaran Mullan, Ivan Timokhin, Takashi Taniguchi, Kenji Watanabe, Alexander N. Grigorenko, Francois Peeters, Kostya S. Novoselov, Qian Yang, Artem Mishchenko
Hydrogen bonding plays a crucial role in biology and technology, yet it remains poorly understood and quantified despite its fundamental importance. Traditional models, which describe hydrogen bonds as electrostatic interactions between electropositive hydrogen and electronegative acceptors, fail to quantitatively capture bond strength, directionality, or cooperativity, and cannot predict the properties of complex hydrogen-bonded materials. Here, we introduce a novel approach that conceptualizes the effect of hydrogen bonds as elastic dipoles in an electric field, which captures a wide range of hydrogen bonding phenomena in various water systems. Using gypsum, a hydrogen bond heterostructure with two-dimensional structural crystalline water, we calibrate the hydrogen bond strength through an externally applied electric field. We show that our approach quantifies the strength of hydrogen bonds directly from spectroscopic measurements and reproduces a wide range of key properties of confined water reported in the literature. Using only the stretching vibration frequency of confined water, we can predict hydrogen bond strength, local electric field, O-H bond length, and dipole moment. Our work also introduces hydrogen bond heterostructures - a new class of electrically and chemically tunable materials that offer stronger, more directional bonding compared to van der Waals heterostructures, with potential applications in areas such as catalysis, separation, and energy storage.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Fine-tuning foundation models of materials interatomic potentials with frozen transfer learning
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
Mariia Radova, Wojciech G. Stark, Connor S. Allen, Reinhard J. Maurer, Albert P. Bartók
Machine-learned interatomic potentials are revolutionising atomistic materials simulations by providing accurate and scalable predictions within the scope covered by the training data. However, generation of an accurate and robust training data set remains a challenge, often requiring thousands of first-principles calculations to achieve high accuracy. Foundation models have started to emerge with the ambition to create universally applicable potentials across a wide range of materials. While foundation models can be robust and transferable, they do not yet achieve the accuracy required to predict reaction barriers, phase transitions, and material stability. This work demonstrates that foundation model potentials can reach chemical accuracy when fine-tuned using transfer learning with partially frozen weights and biases. For two challenging datasets on reactive chemistry at surfaces and stability and elastic properties of tertiary alloys, we show that frozen transfer learning with 10-20% of the data (hundreds of datapoints) achieves similar accuracies to models trained from scratch (on thousands of datapoints). Moreover, we show that an equally accurate, but significantly more efficient surrogate model can be built using the transfer learned potential as the ground truth. In combination, we present a simulation workflow for machine learning potentials that improves data efficiency and computational efficiency.
Materials Science (cond-mat.mtrl-sci)
Structural and superconducting parameters of highly compressed sulfur
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-24 20:00 EST
Evgeny F. Talantsev, Evgeniya G. Valova-Zaharevskaya
Sulfur was the first nonmetal element which was transformed to a superconductor by applying megabar pressure. Recent pioneering experimental developments in measuring the superconducting energy gap \(\Delta(T)\) in compressed sulfur using tunneling spectroscopy (Du \(\textit{et al}\)., \(\textit{Phys. Rev. Lett.}\) \(\textbf{133}\), 036002 (2024)) initiated an interest in better understanding real atomic structure and superconducting properties of this element at high pressure. Here, we analyzed available experimental data on highly compressed sulfur, and, from the \(\Delta(T)\) data reported by Du \(\textit{et al}\). (2024), we extracted the specific heat jump at the transition temperature of \({\Delta}C_{el}/{\gamma}T_{c} = 1.8\). We also developed a model to extract the Debye temperatures \({\Theta}_D\) for sulfur and \(H_{3}S\) in two-phases sample from the temperature-dependent resistance \(R(T)\). for better understanding of material structure, here we proposed to use a size-strain map for highly compressed samples, and we revealed this size-strain map for laser-heated sulfur in a diamond anvil cell with a mixture of sulfur and \(H{_3}S\). Finally, we found that superconducting sulfur exhibits a moderate level of nonadiabaticity \(0.04 \leq {\Theta}_{D}/T_{F} \leq 0.15\) (where \(T_{F}\) is the Fermi temperature), which is similar to \(MgB_2\), pnictides, cuprates, \(La_{4}H_{23}\), \(ThH_{9}\), \(H_{3}S\), \(LaBeH_{8}\), and \(LaH_{10}\).
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
35 pages, 19 figures, 101 references
Local signatures of altermagnetism
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-24 20:00 EST
Jannik Gondolf, Andreas Kreisel, Mercè Roig, Yue Yu, Daniel F. Agterberg, Brian M. Andersen
Altermagnets constitute a class of collinear compensated Néel ordered magnets that break time-reversal symmetry and feature spin-split band structures. Based on versatile microscopic models able to capture the altermagnetic sublattice degrees of freedom, we study characteristic local signatures of altermagnetism near disorder sites. We give a complete list of two-dimensional models that exhibit altermagnetism classified by their corresponding layer groups. Specifically, we calculate the local density of states in the vicinity of pointlike nonmagnetic impurities and expose its spatial dependence for two minimal models showcasing \(d\)-wave and \(g\)-wave altermagnetism. The momentum structure of the nodes (\(d\)-wave, \(g\)-wave, etc.) is directly imprinted on the total local density of states, thus measurable by scanning tunneling conductance experiments. This signature is present both in the spin-resolved as well as the spin-summed local density of states. We find a weaker response in the nonmagnetic state from the anisotropic crystal environment and uncover the importance of the sublattice degree of freedom to model altermagnets. We also study coexistence phases of altermagnetism and superconductivity and provide predictions for the local impurity response of in-gap bound states. The response of impurity bound states strongly enhances the distinct altermagnetic signature.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
The Eggbox Ising Model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-24 20:00 EST
Mutian Shen, Yichen Xu, Zohar Nussinov
We introduce a simple and versatile model that enables controlled design of rugged energy landscapes that realize different types of Parisi overlap distributions. This model captures quintessential aspects of Replica Symmetry Breaking (RSB) theory and may afford additional insights into complex systems and numerical methods for their analysis.
Statistical Mechanics (cond-mat.stat-mech), Computational Physics (physics.comp-ph)
Controlling curvature of self-assembling surfaces via patchy particle design
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-24 20:00 EST
Curved structures in soft matter and biological systems commonly emerge as a result of self-assembly processes where building blocks aggregate in a controlled manner, giving rise to specific system structure and properties. Learning how to precisely tune the curved geometry of these assemblies can in turn elucidate new ways of controlling their functionality. We discuss how one can target self-assembly into surfaces with specified Gaussian curvature in a one-component system of model patchy particles. Given the vast design space of potential patch distributions, we address the problem using an inverse design approach based on automatic differentiation and develop an optimization scheme which solves the exploding gradients problem that arises when we differentiate through long molecular dynamics trajectories. We discuss the model requirements for successful optimization, determine the significant hyperparameter choices influencing algorithm performance and, finally, we demonstrate that we can consistently design patch patterns for assembly into clusters with different target curvature radii.
Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)
Main manuscript: X pages, Y figures. Supplementary Information included
Formation mechanism, stability and role of zinc and sulfur vacancies on the electronic properties and optical response of ZnS
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-24 20:00 EST
P.R.A de Oliveira, L.Lima, G.Felix, P.Venezuela, F.Stavale
Combining experimental and theoretical tools, we report that Zn vacanciesplay an important role in the electronic and optical responses of ZnS sphalerite. The defective surface of ZnS (001) single crystal prepared in ultra-highvacuum conditions, has been shown to exhibit a semiconducting character instead of the insulating properties of the pristine structure, as revealed by X-ray photoelectron spectroscopy (XPS). Interestingly, this effect is attributed to the formation of zinc vacancies in the ZnS system, which also alter the optical response of the material, as supported by photoluminescence (PL) measurements comparing pristine and S-rich (Zn-poor) ZnS. To address these findings from a theoretical point of view, first principles calculations based on density functional theory (DFT) were performed. The optical properties of cation-defective ZnS were evaluated using random-phase approximation and hybrid functional DFT calculations. These calculations revealed absorption peaks in the visible range in the defective ZnS rather than solely in the ultra-violet range obtained for defect-free ZnS. The combination of this finding with joint density of states (JDOS) analysis explains the emergence of new luminescence peaks observed in the PL spectra of cation-defective ZnS. These findings highlight the role of Zn vacancies in tuning ZnS optical properties, making it a potential candidate for optoelectronic applications such as LEDs and photodetectors.
Materials Science (cond-mat.mtrl-sci)
6 Figures. Supporting information available upon request