CMP Journal 2025-04-03
Statistics
Nature: 2
Nature Materials: 3
Nature Physics: 1
Physical Review Letters: 3
arXiv: 67
Nature
Strategic atom replacement enables regiocontrol in pyrazole alkylation
Original Paper | Synthetic chemistry methodology | 2025-04-02 20:00 EDT
Alexander Fanourakis, Yahia Ali, Liao Chen, Patrick Q. Kelly, Abigail J. Bracken, Christopher B. Kelly, Mark D. Levin
Pyrazoles are heterocycles commonly found as key substructures in agrochemicals and medicinally active compounds alike.1,2 Despite their pervasiveness, established methods fall notably short in delivering complex pyrazoles selectively due to issues of differentiation during either assembly or N-functionalization.3 This is a direct consequence of a dominant synthetic strategy that attempts to control selectivity-determining bonds between poorly differentiated starting materials. To overcome this longstanding challenge, we here describe a prototypical example of an alternative conceptual approach, “Strategic Atom Replacement”, in which we synthesize N-alkyl pyrazoles from isothiazoles. The net forward transformation is a “swap” of the isothiazole sulfur atom with a nitrogen atom and its associated alkyl fragment to deliver the alkylated pyrazole.4,5 Linking the two azoles is an orphaned heterocycle class, 1,2,3-Thiadiazine-S-Oxides, whose synthetic potential has yet to be tapped.6 By proceeding via these unusual heterocycles, the typical selectivity and separation challenges associated with exclusively bond-based pyrazole preparations are circumvented, and even minimally differentiated peripheral substituents can be discriminated to afford isomerically pure products.
Synthetic chemistry methodology, Reaction mechanisms
Hidden states and dynamics of fractional fillings in twisted MoTe2 bilayers
Original Paper | Electronic devices | 2025-04-02 20:00 EDT
Yiping Wang, Jeongheon Choe, Eric Anderson, Weijie Li, Julian Ingham, Eric A. Arsenault, Yiliu Li, Xiaodong Hu, Takashi Taniguchi, Kenji Watanabe, Xavier Roy, Dmitri Basov, Di Xiao, Raquel Queiroz, James C. Hone, Xiaodong Xu, X.-Y. Zhu
The fractional quantum anomalous Hall (FQAH) effect was recently discovered in twisted MoTe2 bilayers (tMoTe2)1-4. Experiments to date have revealed Chern insulators from hole doping at ν = -1, -2/3, -3/5, and -4/7 (per moiré unit cell) 1-6. In parallel, theories predict that, between v = -1 and -3, there exist exotic quantum phases 7-15, such as the coveted fractional topological insulators (FTI), fractional quantum spin Hall (FQSH) states, and non-abelian fractional states. Here we employ transient optical spectroscopy 16,17 on tMoTe2 to reveal nearly 20 hidden states at fractional fillings that are absent in static optical sensing or transport measurements. A pump pulse selectively excites charge across the correlated or pseudo gaps, leading to the disordering (melting) of correlated states 18. A probe pulse detects the subsequent melting and recovery dynamics via exciton and trion sensing 1,3,19-21. Besides the known states, we observe additional fractional fillings between ν = 0 and -1 and a large number of states on the electron doping side (ν > 0). Most importantly, we observe new states at fractional fillings of the Chern bands at ν = -4/3, -3/2, -5/3, -7/3, -5/2, and -8/3. These states are potential candidates for the predicted exotic topological phases 7-15. Moreover, we show that melting of correlated states occurs on two distinct time scales, 2-4 ps and 180-270 ps, attributed to electronic and phonon mechanisms, respectively. We discuss the differing dynamics of the electron and hole doped states from the distinct moiré conduction and valence bands.
Electronic devices, Phase transitions and critical phenomena
Nature Materials
Precise synthesis of advanced polyarylamines for efficient perovskite solar cells
Original Paper | Conjugated polymers | 2025-04-02 20:00 EDT
Ziqiu Shen, Yanchun Huang, Yuan Dong, Kangrong Yan, Hongzhen Chen, Chang-Zhi Li
Although being highly demanded in organic electronics, functional conjugated polymers face challenges on scalable synthesis with batch uniformities. Here a reactivity-regulated sequent cross-coupling carbon-nitrogen polycondensation method is developed to enable the precise synthesis of functional polyarylamines with excellent batch-to-batch uniformity. It is revealed that the stepwise regulation of intermediate reactivities is key to accomplish controllable polycondensation via two sequent palladium-promoted carbon-nitrogen coupling cycles, which is distinct to the unicyclic carbon-carbon coupling. A variety of polyarylamines are prepared to improve the material functionalities, where a ternary polymer consisting of polar substituents is shown to optimize the interfacial and bulk properties of perovskite layers fabricated on top. The corresponding inverted perovskite solar cells achieved remarkable power conversion efficiencies of 25.2% (active area, 5.97 mm2) and 23.2% (active area, 128 mm2), along with decent operational stabilities. Overall, this work provides an effective polymerization method for advanced conjugated polymers to enable high-performance optoelectronics.
Conjugated polymers, Solar cells
Biorhythm-mimicking growth hormone patch
Original Paper | Biomedical engineering | 2025-04-02 20:00 EDT
Jinpeng Han, Zhaoyuan Wu, Shumin Zhan, Tao Sheng, Jiahuan You, Jicheng Yu, Junfen Fu, Yuqi Zhang, Zhen Gu
Timing dosing throughout the day impacts the therapeutic efficacy and side effects of medications. Thus, optimizing release profiles to synchronize drug concentrations with natural rhythms is critical for optimal therapeutic benefits. However, existing delivery systems are still inefficient in delivering drugs in a biorhythm-mimicking fashion. Here we describe a biorhythm-inspired growth hormone transdermal microneedle patch with multistage drug release that mimics the natural rhythm of human growth hormone secretion at night. Programmed drug release is achieved by combining a ‘burst-release’ module with several ‘delayed-release’ modules. Compared with the subcutaneous daily injections currently used in clinics, the patch exhibits enhanced efficacy in terms of longitudinal bone growth and bone quality, leading to bone length increases of ~10 mm and ~5 mm in healthy rats and growth hormone gene knockout mice, respectively. Our findings reveal that the biorhythm-mimicking release pattern significantly enhances growth hormone bioavailability and effectively regulates the growth-related biological process, thus boosting the secretion of insulin-like growth factor-1 and ultimately promoting bone growth.
Biomedical engineering, Drug delivery
The influence of pressure on lithium dealloying in solid-state and liquid electrolyte batteries
Original Paper | Batteries | 2025-04-02 20:00 EDT
Congcheng Wang, Yuhgene Liu, Won Joon Jeong, Timothy Chen, Mu Lu, Douglas Lars Nelson, Elif Pınar Alsaç, Sun Geun Yoon, Kelsey Anne Cavallaro, Sazol Das, Diptarka Majumdar, Rajesh Gopalaswamy, Shuman Xia, Matthew T. McDowell
Dealloying reactions underpin the operation of next-generation battery electrodes and are also a synthesis route for porous metals, but the influence of mechanical stress on these processes is not well understood. Here we investigate how the applied stack pressure affects structural evolution and electrochemical reversibility during the alloying/dealloying of Li alloy materials (Li-Al, Li-Sn, Li-In and Li-Si) using solid-state and liquid electrolytes. The extent of porosity formation during the dealloying of metals is found to be universally governed by stack pressure, with pressures of at least 20% of the yield strength required to achieve ~80% relative density. This concept is correlated to the cycling of alloy electrodes in solid-state batteries, with a yield-strength-dependent threshold pressure needed for reversible high Li-storage capacity due to densification. With this understanding, we design Al and Si anodes with a densified interfacial layer enabling stable cycling at low stack pressures (2 MPa), providing guidance towards practical high-energy solid-state batteries.
Batteries, Mechanical engineering
Nature Physics
Hybrid entanglement and bit-flip error correction in a scalable quantum network node
Original Paper | Quantum information | 2025-04-02 20:00 EDT
Xiu-Ying Chang, Pan-Yu Hou, Wen-Gang Zhang, Xiang-Qian Meng, Ye-Fei Yu, Ya-Nan Lu, Yan-Qing Liu, Bin-Xiang Qi, Dong-Ling Deng, Lu-Ming Duan
Recent efforts have succeeded in producing quantum networks in which quantum information can be stored, transferred and processed across multiple nodes on a metropolitan scale. A key remaining challenge is to enhance the capabilities of individual nodes, providing precise and robust control over multiple qubits. Here we demonstrate coherent control in a hybrid quantum node based on a diamond colour centre. We entangle three types of qubit: an electron spin as an interface qubit, a nuclear spin with long memory time and a flying photonic qubit. These qubits’ frequencies span three distinct regimes, from the optical to the radio-frequency domain. By incorporating two additional nuclear spins, we encode three memory qubits into a logical state using a repetition code and entangle this logical qubit with a photonic qubit. We repeatedly read out the error syndromes of memory qubits using the electron interface qubit, then apply real-time feedback operations to correct bit-flip errors. We perform our protocol for up to 12 rounds and demonstrate an improvement in the logical-photonic joint state population compared with its uncorrected counterpart. Our results demonstrate the feasibility of several key functionalities required for quantum repeaters to operate in full-fledged quantum networks.
Quantum information, Single photons and quantum effects
Physical Review Letters
Search for Fractionally Charged Particles in Proton-Proton Collisions at $\sqrt{s}=13\text{ }\text{ }\mathrm{TeV}$
Research article | Particle dark matter | 2025-04-02 06:00 EDT
A. Hayrapetyan et al. (CMS Collaboration)
A search is presented for fractionally charged particles with charges below $1e$, using their small energy loss in the tracking detector as a key variable to observe a signal. The analyzed dataset corresponds to an integrated luminosity of $138\text{ }\text{ }{\mathrm{fb}}^{- 1}$ of proton-proton collisions collected at $\sqrt{s}=13\text{ }\text{ }\mathrm{TeV}$ in 2016–2018 at the CERN LHC. This is the first search at the LHC for new particles with a charge between $e/3$ and $0.9e$, including an extension of previous results at a charge of $2e/3$. Masses up to 640 GeV and charges as low as $e/3$ are excluded at 95% confidence level. These are the most stringent limits to date for the considered Drell-Yan-like production mode.
Phys. Rev. Lett. 134, 131802 (2025)
Particle dark matter, Hypothetical particles, Hadron colliders
Low-Energy Excitations in Bosonic Quantum Quasicrystals
Research article | Bosons | 2025-04-02 06:00 EDT
A. Mendoza-Coto, M. Bonifacio, and F. Piazza
A new theory unveils the exotic low-energy excitations of quasicrystals formed of quantum particles
Phys. Rev. Lett. 134, 136003 (2025)
Bosons, Phasons, Phonons, Quasiparticles & collective excitations, Path integrals
Coulomb Drag in Altermagnets
Research article | Electrical conductivity | 2025-04-02 06:00 EDT
Hao-Jie Lin, Song-Bo Zhang, Hai-Zhou Lu, and X. C. Xie
Coulomb drag resistivity is highly sensitive to the orientation of the altermagnetically induced Fermi surface splitting making it an effective method to probe altermagnetic phases.
Phys. Rev. Lett. 134, 136301 (2025)
Electrical conductivity, Quantum transport, k dot p method
arXiv
Theory of Linear Magnetoresistance in a Strange Metal
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Jaewon Kim, Shubhayu Chatterjee
A central puzzle in strongly correlated electronic phases is strange metallic transport, marked by $ T$ -linear resistivity and $ B$ -linear magnetoresistance, in sharp contrast with quadratic scalings observed in conventional metals. Here, we demonstrate that proximity to quantum critical points, a recurring motif in the phase diagrams of strange metal candidates, can explain both transport anomalies. We construct and solve a minimal microscopic model by coupling electronic excitations at the Fermi surface to quantum critical bosons via a spatially disordered Yukawa interaction, as well as static pinned domains of density wave order. The resultant transport relaxation rate scales as $ k_B T/\hbar$ at low magnetic fields, and as an effective Bohr magneton $ \tilde{\mu}_B B/\hbar$ at low temperatures. Further, the magnetoresistance in our model shows a scaling collapse upon rescaling the magnetic field and the resistance by temperature, in agreement with experimental observations.
Strongly Correlated Electrons (cond-mat.str-el)
5 + 5 pages, 3 figures
Identifying biases of the Majorana scattering invariant
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-03 20:00 EDT
Isidora Araya Day, Antonio L. R. Manesco, Michael Wimmer, Anton R. Akhmerov
The easily accessible experimental signatures of Majorana modes are ambiguous and only probe topology indirectly: for example, quasi-Majorana states mimic most properties of Majoranas. Establishing a correspondence between an experiment and a theoretical model known to be topological resolves this ambiguity. Here we demonstrate that already theoretically determining whether a finite system is topological is by itself ambiguous. In particular, we show that the scattering topological invariant – a probe of topology most closely related to transport signatures of Majoranas – has multiple biases in finite systems. For example, we identify that quasi-Majorana states also mimic the scattering invariant of Majorana zero modes in intermediate-sized systems. We expect that the bias due to finite size effects is universal, and advocate that the analysis of topology in finite systems should be accompanied by a comparison with the thermodynamic limit. Our results are directly relevant to the applications of the topological gap protocol.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 4 figures
Chiral vortex-line liquid of three-dimensional interacting Bose systems with moat dispersion
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Bahar Jafari-Zadeh, Chenan Wei, Tigran A. Sedrakyan
We formulate and investigate a novel quantum state, the Chiral Vortex-Line Liquid (CVLL), emerging in three-dimensional interacting Bose systems exhibiting moat-band dispersions. Such dispersions feature extensive degeneracy along closed manifolds in momentum space, significantly amplifying quantum fluctuations that suppress conventional Bose-Einstein condensation. By extending the two-dimensional Chern-Simons flux-attachment transformation to three dimensions through a combination of planar CS phases and Jordan-Wigner fermionization along vortex lines, we construct the CVLL state, characterized by nontrivial vortex-line excitations with topological properties. We develop an associated topological field theory in a curved spatial geometry and study the low-energy effective theory of the CVLL state. Using Monte Carlo simulations, we numerically determine the CVLL ground state’s chemical potential for interacting bosons in cylindrical moat-band geometries and demonstrate that the CVLL phase energetically outcompetes traditional condensate phases at low densities, highlighting its relevance to experimental platforms including frustrated quantum magnets, ultracold atomic gases, physics of rotons in $ ^4$ He, and moat regimes in heavy-ion collisions.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Gases (cond-mat.quant-gas), High Energy Physics - Theory (hep-th)
23 pages, 10 figures
Surfactants Screen Slide Electrification
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-03 20:00 EDT
Xiaomei Li, Zhongyuan Ni, Xiaoteng Zhou, Lisa S. Bauer, Diego Diaz, Gabriele Schäfer, Hans-Jürgen Butt
Water drops spontaneously accumulate charges when they move on hydrophobic dielectric surfaces by slide electrification. On the one hand, slide electrification generates electricity with possible applications on tiny devices. On the other hand, the potential of up to 1 KV generated by slide electrification alters wetting and drop motion. Therefore, it is important to know the factors that affect slide electrification. To find out how surfactants affect slide electrification, we measured drop charges of aqueous drops containing cationic CTAB, anionic SDS and neutral C8E3 sliding on different hydrophobic surfaces. The result is: addition of surfactant significantly reduces the spontaneous charging of moving water drops. Based on zeta potential measurements, confocal microscopy of deposited surface-active dyes and drop impact studies, we propose that several factors contribute to this suppression of charge separation: (1) Surfactants tend to lower the contact angles, which reduces charge separation. (2) Surfactant adsorption at the solid-liquid interface can reduce the density of primary ions, particularly for anionic surfactants. (3) Anionic and neutral surfactants are mostly transferred to the liquid-air interface at the rear of the sliding drop, retaining primary ions within the drop. (4) Deposited cationic surfactant directly reduces the charge of the drop.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
13 pages, 4 figures, 50 references
Pressure-induced orbital reordering in Na$_2$CuF$_4$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Craig I. Hiley, Catriona A. Crawford, Craig L. Bull, Nicholas P. Funnell, Urmimala Dey, Nicholas C. Bristowe, Richard I. Walton, Mark S. Senn
The high-pressure behaviour of Na$ _2$ CuF$ _4$ is explored by powder neutron diffraction and density functional theory (DFT) calculations. A first-order phase transition is observed to take place between 2.4 - 2.9 GPa, involving a reorientation of the Jahn-Teller (JT) long axes of the (CuF6) octahedra (and therefore the d$ _{z^2}$ Cu orbitals), in agreement with our DFT calculations which suggest a transition at 2.8 GPa. The transition can be described as being between a state of ferro-orbital order and one of A-type antiferro-orbital order, reflecting a shift in the associated electronic instability from being in the zone-center to zone boundary of the first Brillouin zone of the parent structure, with pressure. This change results in a decoupling of magnitude of the associated Jahn-Teller distortion of the Cu-F bond lengths from the lattice strain. This scenario is supported by our observations that the compressibility of the pre-transition phase is highly anisotropic, whilst in the post-transition phase it becomes almost isotropic, and that we observed no further decrease of the magnitude the JT distortion up to 5 GPa, or melting of the OO in our DFT calculations up to at least 5 GPa.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
7 Pages, 5 Figures
Creating mixed-phase states in cadmium sulfide by swift heavy ion irradiation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Aldo Artímez Peña, Nikita Medvedev
CdS has broad applications in solar cells and radiation detectors. We study its response to irradiation with swift heavy ions and determine its damage thresholds. We apply a model combining the Monte Carlo code TREKIS-3 to simulate the kinetics of the electronic system and the molecular dynamics code LAMMPS to track the atomic reaction to the energy transfer. It is found that ion tracks in CdS differ between its zincblende and wurtzite phases in morphology and damage thresholds. The anisotropic wurtzite phase displays directional damage formation with transient hexagonal track shapes along the (001) plane. In contrast, zincblende CdS exhibits a more cylindrical damage distribution. High pressures near the ion path drive mass transport away from the melted region, forming cavities within the track core in the wurtzite phase. Although significant recrystallization is observed during post-irradiation relaxation, it does not fully restore the original phase: final tracks consist of the amorphous cores due to the low densities in this region and defect-containing crystalline halos. These findings suggest that ion irradiation could be used to create mixed-phase CdS-based materials.
Materials Science (cond-mat.mtrl-sci)
Silk: A promising natural blend of amino acids for efficient CO2 capture
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Md Sariful Sheikh, Qiyuan Chen, Lijie Guo, Xudong Wang, Bu Wang
In recent years, various highly porous solid sorbents have drawn a significant research interest as promising carbon capture material. Nevertheless, the issues of high synthesis cost, limited CO2 adsorption capacity, slow adsorption-desorption kinetics, high sorbent regeneration temperature, and poor operational stability remain challenges to overcome before their practical implementation. Herein, natural silk fibroin, a blend of various amino acids, could be a promising material to realize low-cost carbon capture technology due to its amine-like CO2 capture behavior, light weight, natural abundance, scalable processing, and biocompatibility. The mulberry silk-derived silk-fibroin aerogel with a high specific surface area demonstrates high CO2 adsorption capacity (~3.65 mmol CO2/gm sorbent at 0.15 atm CO2), which is competitive with state-of-the-art solid sorbents and surpasses all amino acid-based solid sorbents. The thermogravimetry analysis reveals that the thermal degradation temperature of silk-fibroin aerogel is around 250 oC, significantly higher than conventional amines used for carbon capture. Furthermore, the silk-fibroin-based sorbent demonstrates rapid adsorption-desorption kinetics, complete regeneration at a temperature as low as 60 oC, promising stability over multiple adsorption-desorption cycles, and maintaining its adsorption capacity under humid conditions. Overall, this study highlights natural silk’s promising carbon capture potential, which is demanding further exploration.
Materials Science (cond-mat.mtrl-sci)
α-Ta (111) Thin Films for Qubit Applications: A Study of Thickness Dependence and Universal Scaling
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Nate Price, Jose Gutiérrez, Sushant Padhye, Sara McGinnis, Carter Wade, Huma Yusuf, Lakshan Don Manuwelge Don, Kurt Eyink, J. Guerrero-Sánchez, Evgeny Mikheev, Joseph P. Corbett
We explore the growth of {\alpha}-Ta thin films ranging from ultra-thin (2 nm) to thick (250 nm) films grown by sputter epitaxy on c-plane sapphire substrates. We utilized 100 W power with a 32 mTorr sputter pressure at 650 ° substrate deposition temperature. We used X-ray diffractometry to extract the lattice constant and growth orientation of the films, finding a mono-oriented (111) films with a lattice spacing in agreement with a bulk Ta value of 3.31 Å. X-ray reflectometry is used to characterize the native oxide, film, and substrate-film interface as a function of thickness. We observe a very smooth morphology with an average roughness of 700 pm, as determined by both reflectometry and atomic force microscopy. The film nucleates with small islands, whose terrace width grows linearly as a function of thickness until 150 nm, where the terrace width becomes constant. From our reflectometry measurements, we uncover a pseudomorphic layer with a critical thickness of 1 nm and a self-limiting amorphous oxide that grows to a thickness of 2.25 nm; both of these layers are independent of thickness beyond 4 nm total thickness. We also studied the superconducting transition through electronic transport measurements using the Van der Pauw method to measure resistivity as a function of temperature. We observed a smooth evolution in critical superconducting temperature with total film thickness, from 2.9 °K for 7.5 nm to 4.2 °K for 269.2 nm, as expected from universal thickness scaling in superconductors. Density functional theory simulations were used to understand the oxidation process at the top surface layers of {\alpha}-Ta (111). We observed that as the oxygen content on the surface increases, the Ta progressively loses its crystalline structure. Significant structural distortions occur when the Ta:O ratio exceeds 1:1, forming an amorphous TaO phase.
Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
Shaking and pushing skyrmions: Formation of a non-equilibrium phase with zero critical current
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Felix Rucker, Alla Bezvershenko, Denis Mettus, Andreas Bauer, Markus Garst, Achim Rosch, Christian Pfleiderer
In three-dimensional chiral magnets, skyrmions are line-like objects oriented parallel to the applied magnetic field. The efficient coupling of magnetic skyrmion lattices to spin currents and magnetic fields permits their dynamical manipulation. Here, we explore the dynamics of skyrmion lattices when slowly oscillating the field direction by up to a few degrees on millisecond timescales while simultaneously pushing the skyrmion lattice by electric currents. The field oscillations induce a shaking of the orientation of the skyrmion lines, leading to a phase where the critical depinning current for translational motion vanishes. We measure the transverse susceptibility of MnSi to track various depinning phase transitions induced by currents, oscillating fields, or combinations thereof. An effective slip–stick model for the bending and motion of the skyrmion lines in the presence of disorder explains main features of the experiment and predicts the existence of several dynamical skyrmion lattice phases under shaking and pushing representing new phases of matter far from thermal equilibrium.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Indirect Excitons and Many-body Interactions in InGaAs Double Quantum Wells
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-03 20:00 EDT
Christopher L. Smallwood, Rachel Owen, Matthew W. Day, Takeshi Suzuki, Rohan Singh, Travis M. Autry, Smriti Bhalerao, Fauzia Jabeen, Steven T. Cundiff
Spatially indirect excitons in semiconductor quantum wells are relevant to basic research and device applications because they exhibit enhanced tunability, delocalized wave functions, and potentially longer lifetimes relative to direct excitons. Here we investigate the properties of indirect excitons and their coupling interactions with direct excitons in asymmetric InGaAs double quantum wells using optical multidimensional coherent spectroscopy and photoluminescence excitation spectroscopy. Analyses of the spectra confirm a strong influence of many-body effects, and reveal that excited-state zero-quantum coherences between direct and indirect excitons in the quantum wells dephase faster than the much higher-energy single-quantum coherences between excitonic excited states and ground states. The results also suggest an important energy-dependent role of continuum states in mediating system dynamics, and they indicate that dephasing mechanisms are associated with uncorrelated or anticorrelated energy-level fluctuations.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
10 pages, 7 figures, submitted to Physical Review B
Quantitative approaches for multi-scale structural analysis with atomic resolution electron microscopy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Noah Schnitzer, Lopa Bhatt, Ismail El Baggari, Robert Hovden, Benjamin H. Savitzky, Michelle A. Smeaton, Berit H. Goodge
Atomic-resolution imaging with scanning transmission electron microscopy is a powerful tool for characterizing the nanoscale structure of materials, in particular features such as defects, local strains, and symmetry-breaking distortions. In addition to advanced instrumentation, the effectiveness of the technique depends on computational image analysis to extract meaningful features from complex datasets recorded in experiments, which can be complicated by the presence of noise and artifacts, small or overlapping features, and the need to scale analysis over large representative areas. Here, we present image analysis approaches which synergize real and reciprocal space information to efficiently and reliably obtain meaningful structural information with picometer scale precision across hundreds of nanometers of material from atomic-resolution electron microscope images. Damping superstructure peaks in reciprocal space allows symmetry-breaking structural distortions to be disentangled from other sources of inhomogeneity and measured with high precision. Real space fitting of the wave-like signals resulting from Fourier filtering enables absolute quantification of lattice parameter variations and strain, as well as the uncertainty associated with these measurements. Implementations of these algorithms are made available as an open source Python package.
Materials Science (cond-mat.mtrl-sci), Data Analysis, Statistics and Probability (physics.data-an)
18 pages, 13 figures
Minimal pole representation for spectral functions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Lei Zhang, André Erpenbeck, Yang Yu, Emanuel Gull
Representing spectral densities, real-frequency, and real-time Green’s functions of continuous systems by a small discrete set of complex poles is an ubiquitous problem in condensed matter physics, with applications ranging from quantum transport simulations to the simulation of strongly correlated electron systems. This paper introduces a method for obtaining a compact, approximate representation of these functions, based on their parameterization on the real axis and a given approximate precision. We show applications to typical spectral functions and results for structured and unstructured correlation functions of model systems.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Reset Induced Multimodality in Unbounded Potential
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-03 20:00 EDT
Resetting, as a protocol that restarts the evolution of a system, can significantly influence stochastic dynamics. One notable effect is the emergence of stationary states in unbounded potentials, where such states would otherwise be absent without resetting. In this work, we explore unbounded potentials for which resetting not only induces stationary states but also leads to their multimodality, despite the repulsive nature of the potential. We present examples of potentials that, despite lacking local minima, can generate trimodal and pentamodal states, and we investigate how the modal structure of these states varies with noise intensity and resetting frequency.
Statistical Mechanics (cond-mat.stat-mech)
7 pages, 7 figures
Computational Study of Density Fluctuation-Induced Shear Bands Formation in Bulk Metallic Glasses
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Siya Zhu, Hagen Eckert, Stefano Curtarolo, Jan Schroers, Axel van de Walle
Seemingly identical Bulk Metallic Glasses (BMG) often exhibit strikingly different mechanical properties despite having the same composition and fictive temperature. A postulated mechanism underlying these differences is the presence of “defects”. Here we investigate this hypothesis through the study of the effect of density fluctuations on shear band formation under an applied stress. We find that the critical shear stress is strongly dependent on the magnitude and size of the fluctuations. This finding also elucidates why, historically, critical shear stresses obtained in simulations have differed so much from those found experimentally, as typical simulations setups might favor unrealistically uniform geometries.
Materials Science (cond-mat.mtrl-sci)
TCNQ self-assembly driven by molecular coverage over borophene monolayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Boron monolayers, also known as borophene, have recently attracted interest due to their electronic properties, e.g. the facility to form various allotropes with interesting properties. In this work, we investigate the adsorption process of the tetracyanoquinodimethane (TCNQ) on the borophene $ \beta_{12}$ and $ \chi_3$ using the density functional theory (DFT). We observed that molecules bond to the borophene layer through the van der Waals interaction, where, at the low coverage limit, the binding strength of TCNQ / borophene is comparable to that of TCNQ / WSe$ _2$ . By increasing the molecular coverage, $ 10^{13} \rightarrow 10^{14}$ molecules/cm$ ^{2}$ , we found the (exothermic) formation of self-assembled (SA) structures of TCNQ on borophene, where the molecule-molecule interactions rule the SA process. The structural stability of the SA-TCNQ molecule on borophene was verified via ab initio molecular dynamics simulations. Finally, we show that the formation of the vdW interface leads to the tunability of the hole-doping of the borophene layer by an external electric field. We believe that our results bring an important contribution to the atomic-scale understanding of a powerful electron acceptor molecule, TCNQ, adsorbed on a promising 2D material, borophene.
Materials Science (cond-mat.mtrl-sci)
7 pages, 6 figures
Hydrodynamics of the electronic Fermi liquid: a pedagogical overview
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
For over a hundred years, electron transport in conductive materials has been primarily described by the Drude model, which assumes that current flow is impeded primarily by momentum-relaxing collisions between electrons and extrinsic objects such as impurities or phonons. In the past decade, however, experiments have increasingly realized ultra-high quality electronic materials that demonstrate a qualitatively distinct method of charge transport called hydrodynamic flow. Hydrodynamic flow occurs when electrons collide much more frequently with each other than with anything else, and in this limit the electric current has long-wavelength collective behavior analogous to that of a classical fluid. While electron hydrodynamics has long been postulated theoretically for solid-state systems, the plethora of recent experimental realizations has reinvigorated the field. Here, we review recent theoretical and experimental progress in understanding hydrodynamic electrons using the (hydrodynamic) Fermi liquid as our prototypical example.
Strongly Correlated Electrons (cond-mat.str-el)
18 pages, 7 figures + references; invited topical review to IOP Journal of Physics: Condensed Matter
Multicriticality in stochastic dynamics protected by self-duality
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-03 20:00 EDT
Konstantinos Sfairopoulos, Luke Causer, Juan P. Garrahan
We study the dynamical large deviations (LD) of a class of one-dimensional kinetically constrained models whose (tilted) generators can be mapped into themselves via duality transformations. We consider four representative models in detail: the domain-wall (DW) Fredrickson-Andersen (FA), the DW East, the ZZZ-FA, and the XOR-FA models. Using numerical tensor networks, we build the LD phase diagrams of these models in terms of the softness of the constraint and the counting field conjugate to the dynamical activity. In all cases, we find distinct dynamical phases separated by phase transitions along the self-dual lines, revealing the presence of multi-critical points that delimit first-order from continuous active-inactive transitions. We discuss connections to supersymmetry and possible extensions to higher spin and space dimensions.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
8 pages, 3 figures
Bayesian critical points in classical lattice models
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-03 20:00 EDT
Adam Nahum, Jesper Lykke Jacobsen
The Boltzmann distribution encodes our subjective knowledge of the configuration in a classical lattice model, given only its Hamiltonian. If we acquire further information about the configuration from measurement, our knowledge is updated according to Bayes’ theorem. We examine the resulting “conditioned ensembles”, finding that they show many new phase transitions and new renormalization-group fixed points. (Similar conditioned ensembles also describe “partial quenches” in which some of the system’s degrees of freedom are instantaneously frozen, while the others continue to evolve.) After describing general features of the replica field theories for these problems, we analyze the effect of measurement on illustrative critical systems, including: critical Ising and Potts models, which show surprisingly rich phase diagrams, with RG fixed points at weak, intermediate, and infinite measurement strength; various models involving free fields, XY spins, or flux lines in 2D or 3D; and geometrical models such as polymers or clusters. We make connections with quantum dynamics, in particular with “charge sharpening” in 1D, by giving a formalism for measurement of classical stochastic processes: e.g. we give a purely hydrodynamic derivation of the known effective field theory for charge sharpening. We discuss qualitative differences between RG flows for the above measured systems, described by $ N\to 1$ replica limits, and those for disordered systems, described by $ N\to 0$ limits. In addition to discussing measurement of critical states, we give a unifying treatment of a family of inference problems for non-critical states. These are related to the Nishimori line in the phase diagram of the random-bond Ising model, and are relevant to various quantum error correction problems. We describe distinct physical interpretations of conditioned ensembles and note interesting open questions.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Physics (quant-ph)
59 pages, 10 figures
Low-energy structure and topology of the two-band Hubbard-Kanamori model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Nayara G. Gusmão, Germán Blesio, Armando Aligia, Walber H. Brito, Maria C. O. Aguiar, Karen Hallberg
We investigate the Mott transition in a two-band Hubbard-Kanamori model using Dynamical Mean-Field Theory (DMFT) with the Density Matrix Renormalization Group (DMRG) and the Numerical Renormalization Group (NRG) as impurity solvers. Our study focuses on the case where the intraorbital and interorbital Coulomb interactions are equal (U = U2) and the Hund’s coupling is absent (J = 0). Spectral analysis confirms the absence of an orbital-selective Mott transition (OSMT), even in systems with significantly different bandwidths (t1 and t2 for the wide and narrow bands, respectively), indicating a simultaneous Mott transition in both bands. Notably, the NRG results reveal the emergence of a pseudo-gap-like feature and a central peak in the narrow band, whose characteristics depend on the hopping parameter t2. These spectral features may serve as precursors to OSMT in more realistic systems with finite Hund’s coupling (J > 0). Furthermore, in the Mott insulating phase, the self-energies of both bands diverge, suggesting that the Mott transition represents a topological phase transition. Our results highlight the crucial role of accurate impurity solvers in capturing the density of states and detailed spectral structures.
Strongly Correlated Electrons (cond-mat.str-el)
Triplet superconductivity by the orbital Rashba effect at surfaces of elemental superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-03 20:00 EDT
Tom G. Saunderson, Dongwook Go, Maria Teresa Mercaldo, Mario Cuoco, Mathias Kläui, James F. Annett, Martin Gradhand, Jacob Gayles, Yuriy Mokrousov
It is often assumed that in a superconductor without spin-triplet pairing, the formation of unconventional spin-triplet densities requires the spin-orbit interaction in combination with either broken inversion symmetry or broken time-reversal symmetry. Here, we show from first principles the existence of supercurrent-driven spin triplet densities on the surface of a variety of simple superconducting materials without spin-orbit coupling. We are able to attribute this phenomenon to the superconducting non-relativistic orbital Rashba Edelstein effect. Furthermore, we find that the spin-orbit induced spin moment is one order of magnitude smaller than the orbital moment, and has a vanishing effect on the total magnitude of the induced triplet density. Our findings imply the existence of a route to generate spin-currents without the use of heavy metals. Additionally, as an orbital moment can couple directly to a magnetic field, it shows that orbital physics is the dominant term that drives the superconducting diode effect.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Energy Bands and Breakdown Characteristics in Al2O3/UWBG AlGaN Heterostructures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Seungheon Shin, Kyle Liddy, Yinxuan Zhu, Chandan Joishi, Brianna A. Klein, Andrew Armstrong, Andrew A. Allerman, Siddharth Rajan
We report on energy bands and breakdown characteristics of Al2O3 dielectrics on ultra-wide bandgap (UWBG) AlGaN heterostructures. Metal-dielectric-semiconductor structures are important to sustain high fields needed for future high-performance UWBG transistors. Using systematic experiments, we determined the fixed charge density (> 1013 cm-2), the dielectric/interface, and electric fields in the oxide of under flat-band conditions in the semiconductor. Low gate-to-drain leakage current of up to 5 x 10-7 A/cm2 were obtained in the metal-oxide-semiconductor structures. In lateral metal-semiconductor-insulator test structures, breakdown voltage exceeding 1 kV was obtained with a channel sheet charge density of 1.27 x 1013 cm-2. The effective peak electric field and average breakdown field were estimated to be > 4.27 MV/cm and 1.99 MV/cm, respectively. These findings demonstrate the potential of Al2O2 integration for enhancing the breakdown performance of UWBG AlGaN HEMTs.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
11 pages, 6 figures, and 3 tables
Weyl Semimetals: from Principles, Materials to Applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Mengyuan Zhong, Nam Thanh Trung Vu, Wenhao Zhai, Jian Rui Soh, Yuanda Liu, Jing Wu, Ady Suwardi, Huajun Liu, Guoqing Chang, Kian Ping Loh, Weibo Gao, Cheng-Wei Qiu, Joel K. W. Yang, Zhaogang Dong
Weyl semimetals have attracted significant interest in condensed matter physics and materials science, due to their unique electronic and topological properties. These characteristics not only deepen our understanding of fundamental quantum phenomena, but also make Weyl semimetals promising candidates for advanced applications in electronics, photonics, and spintronics. This review provides a systematic overview of the field, covering theoretical foundations, material synthesis, engineering strategies, and emerging device applications. We first outline the key theoretical principles and distinctive properties of Weyl semimetals, followed by an examination of recent advancements that enhance their functional versatility. Finally, we discuss the critical challenges hindering their practical implementation and explore future development directions, along with the potential for expanding and enhancing their existing range of applications. By integrating discussions of both opportunities and obstacles, this review offers a balanced perspective on current progress and future directions in Weyl semimetal research.
Materials Science (cond-mat.mtrl-sci)
Robustness of ferromagnetism in van der Waals magnet Fe$_3$GeTe$_2$ to hydrostatic pressure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Yonglin Wang, Xu-Tao Zeng, Bo Li, Cheng Su, Takanori Hattori, Xian-Lei Sheng, Wentao Jin
Two-dimensional van der Waals ferromagnet Fe$ _3$ GeTe$ _2$ (FGT) holds a great potential for applications in spintronic devices, due to its high Curie temperature, easy tunability, and excellent structural stability in air. Theoretical studies have shown that pressure, as an external parameter, significantly affects its ferromagnetic properties. In this study, we have performed comprehensive high-pressure neutron powder diffraction (NPD) experiments on FGT up to 5 GPa, to investigate the evolution of its structural and magnetic properties with hydrostatic pressure. The NPD data clearly reveal the robustness of the ferromagnetism in FGT, despite of an apparent suppression by hydrostatic pressure. As the pressure increases from 0 to 5 GPa, the Curie temperature is found to decrease monotonically from 225(5) K to 175(5) K, together with a dramatically suppressed ordered moment of Fe, which is well supported by the first-principles calculations. Although no pressure-driven structural phase transition is observed up to 5 GPa, quantitative analysis on the changes of bond lengths and bond angles indicate a significant modification of the exchange interactions, which accounts for the pressure-induced suppression of the ferromagnetism in FGT.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
6 figures
Chinese Physics B 34, 046203 (2025)
Decoupled anisotropic Charge-Phonon Transport Enables Exceptional n-Type Thermoelectric Performance in CuBiSCl$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Yu Wu, Ying Chen, Shuming Zeng, Liujiang Zhou, Chenhan Liu
First-principles calculations demonstrate an exceptional decoupling of charge and thermal transport along the \textit{a}-axis in CuBiSCl$ _2$ . The material achieves superior electron mobility (138 cm$ ^2$ /V$ \cdot$ s at 300 K) through delocalized Bi-6\textit{p}/S-3\textit{p} networks while maintaining ultralow lattice thermal conductivity (0.40 W/mK at 300 K) via Cu-dominated anharmonic phonon scattering - both optimized along the same crystallographic direction. This simultaneous optimization originates from the anisotropic bonding hierarchy where [BiSCl$ _2$ ]$ _n$ ribbons enable efficient charge transport along \textit{a}-axis, while the soft vibrational modes associated with Cu atoms strongly scatter heat-carrying phonons. The resulting high power factor (1.71 mW/mK$ ^2$ at 700 K) and peak \textit{ZT} of 1.57 establish CuBiSCl$ _2$ as a model system that realizes the long-sought “phonon glass-electron crystal” paradigm through crystallographically engineered transport channels.
Materials Science (cond-mat.mtrl-sci)
Plasmonic Crystals with Tunable Band Gaps in the Grating Gate Transistor Structures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-03 20:00 EDT
G. R. Aizin, J. Mikalopas, M. Shur
We developed a hydrodynamic model of plasmonic crystals formed in the current-driven grating gate transistor structures. The model demonstrates that the quality factor of plasmonic resonances could be increased by using ungated regions with high electron densities connecting multiple plasmonic cavities. The analytical and numerical calculations of the EM radiation absorption by the band plasmons show that the drive current makes all plasma modes optically active by breaking the symmetry of the plasma oscillations. This effect results in splitting plasmon resonant absorption peaks revealing the gaps in the plasmonic band spectrum tunable by current. The analyzed design could achieve resonant behavior at room temperature for plasmonic crystals implemented in various material systems, including graphene, III-V, III-N materials, and p-diamond. We argue that the resulting double-peak spectrum line in the terahertz range also facilitates the absorption at the gap frequency, typically in microwave range. Power pumping at the gap frequency enables excitation of the gap plasmons, promoting frequency conversion from microwave to THz ranges. The flexibility in the length of the ungated region for the investigated structures allows for an effective coupling with THz radiation, with the metal grating acting as a distributive resonant antenna. The applications of the presented results extend to THz communication systems, THz sensing and imaging, frequency conversion systems, and other advanced THz plasmonic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 5 figures
Topological delocalization against Anderson localization observed in Bi-doped PbSb2Te4 disordered topological insulator
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Yuya Hattori, Koichiro Yaji, Keisuke Sagisaka, Shunsuke Yoshizawa, Shunsuke Tsuda, Yuki Tokumoto, Taichi Terashima, Shinya Uji, Keiichi Edagawa
We experimentally investigate the tendency of localization in the bulk and the topological surface states in topological insulators Pb(Bi1-xSbx)2Te4 (x=0.793-0.818) through detailed transport measurements. The bulk electronic states in the range 0.793<=x<0.818 are situated on the insulator side of the Anderson transition, as indicated by k_Fl values (where k_F is the Fermi wavenumber and l is the mean free path) falling below the Ioffe-Regel criterion (i.e., k_F l<1). In contrast, the topological surface states retain high mobility and even exhibit quantum oscillations, demonstrating their resilient nature against strong disorder. These findings highlight the delocalized nature of the topological surface states despite Anderson localization of the bulk electronic states.
Materials Science (cond-mat.mtrl-sci)
18+3 pages, 2+1 figures
Subcritical Pitchfork Bifurcation Transition of a Single Nanoparticle in Strong Confinement
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-03 20:00 EDT
Confinement influences fluid properties. We show, employing molecular dynamics simulations with explicit solvents, that slit confinement drives a first-order transition for a small nanoparticle between staying at the slit center and binding to the slit surfaces. The transition follows a subcritical pitchfork bifurcation, accompanying a similar transition of the nanoparticle’s lateral diffusion, depending on interparticle interactions and confinement interfaces. Our findings underscore the necessity for advancing molecular hydrodynamics under strong confinement.
Soft Condensed Matter (cond-mat.soft), Chemical Physics (physics.chem-ph)
Double unstable avoided crossings and complex domain patterns formation in spin-orbit coupled spin-1 condensates
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-03 20:00 EDT
Sanu Kumar Gangwar, Rajamanickam Ravisankar, Henrique Fabrelli, Paulsamy Muruganandam, Pankaj Kumar Mishra
We analyze the impact of spin-orbit and Rabi couplings on the dynamical stability of spin-orbit-coupled spin-1 Bose-Einstein condensates for ferromagnetic (FM) and antiferromagnetic (AFM) interactions. Determining the collective excitation spectrum through Bogoliubov-de-Gennes theory, we characterize the dynamical stability regime via modulational instability. For AFM interactions, the eigenspectrum reveals the presence of both stable and unstable avoided crossings (UAC), with the first-excited branch undergoing a double unstable avoided crossing. In contrast, with ferromagnetic interactions, only a single UAC, which occurs between the low-lying and first-excited branches, is observed. Furthermore, the eigenvectors demonstrate the transition from density-like to spin-like behaviour, as the collective excitation shows the transition from stable to unstable mode for both the FM and AFM interactions. In the multi-band instability state, eigenvectors display spin-density mixed mode, while they show spin-flip nature in the avoided crossing regime. Our analysis suggests that spin-orbit coupling enhances the instability gain, while Rabi coupling plays the opposite role. Finally, we corroborate our analytical findings of stable and unstable regimes through numerical simulations of the dynamical evolution of the condensates by introducing the perturbations upon quenching the trap strength. The dynamical phases show the formation of complex domains with AFM interaction, which may be attributed to the double unstable avoided crossings in such a system.
Quantum Gases (cond-mat.quant-gas)
17 pages, 15 figures
A steady solution to the hydrodynamic equation and incommensurate magnetization in a U(2) invariant superfluid
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-03 20:00 EDT
At the zero temperature limit, a one-dimensional steady solution to the hydrodynamic equation of a U(2) invariant superfluid is obtained. This solution reveals that the magnitude of magnetization is always directly proportional to the particle number density. Furthermore, the problem can be interpreted as a particle’s motion in a central force field. It is demonstrated that the particle’s orbits are elliptical in shape, with a precession angle determined by a non-zero mass current. This suggests that the spatial periods of the three component magnetizations are not commensurate. These findings indicate that the coupling of mass superflow and magnetization distortions usually results in an incommensurate magnetization.
Quantum Gases (cond-mat.quant-gas)
9 figures
Temperature and misorientation-dependent austenite nucleation at ferrite grain boundaries in a medium manganese steel: role of misorientation-dependent grain boundary segregation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Rama Srinivas Varanasi, Osamu Waseda, Faisal Waqar Syed, Prithiv Thoudden-Sukumar, Baptiste Gault, Jörg Neugebauer, Dirk Ponge
In the current work, we study the role of grain boundary (GB) misorientation-dependent segregation on austenite nucleation in a 50% cold rolled intercritically annealed 10Mn-0.05C-1.5Al (wt. %) medium Mn steel. During intercritical annealing at 500°C, austenite nucleates predominantly at high-angle GBs. At 600°C, austenite nucleates additionally at low-angle GBs, exhibiting a temperature dependance. Correlative transmission Kikuchi diffraction /atom probe tomography reveals a misorientation-dependent segregation. While GB segregation has been reported to assist austenite nucleation in medium manganese steels (3-12 wt.% Mn), an understanding of the temperature and misorientation dependance is lacking, which is the aim of current work. Since artifacts of atom probe can cause a broadening of the segregation width, we combined experiments with results from density functional theory (DFT) calculations that reveal that the Mn segregation is not limited to the GB plane but confined to a region in the range of approximately 1 nm. Consequently, GB segregation alters both the GB interface energy and the free energy per unit volume corresponding to the transformation. We estimate the local driving force for austenite nucleation accounting for the segregation width of ~ 1 nm. Based on classical nucleation theory, we clarify the effect of GB segregation on the critical radius and activation energy barrier for confined austenite nucleation at the GB.
Materials Science (cond-mat.mtrl-sci)
Fate of Berezinskii-Kosterlitz-Thouless Paired Phase in Coupled $XY$ Models
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-03 20:00 EDT
Tianning Xiao, Youjin Deng, Xiao-Yu Dong
Intriguing phases may emerge when two-dimensional systems are coupled in a bilayer configuration. In particular, a Berezinskii-Kosterlitz-Thouless (BKT) paired superfluid phase was predicted and claimed to be numerically observed in a coupled $ XY$ model with ferromagnetic interlayer interactions, as reported in [\href{this https URL}{Phys. Rev. Lett. 123, 100601 (2019)}]. However, both our Monte Carlo simulations and analytical analysis show that this model does not exhibit a BKT paired phase. We then propose a new model incorporating four-body interlayer interactions to realize the BKT paired phase. Moreover, we observe that the anomalous magnetic dimension varies along the phase transition line between the disordered normal phase and the BKT paired phase. This finding requires an understanding beyond the conventional phase transition theory.
Statistical Mechanics (cond-mat.stat-mech)
Mechanisms of Dual-Band Emission in Sb-Doped Rare-Earth Phosphates Revealed
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Ruijie Hao, Xin Zhao, Chang-Kui Duan
The Sb$ ^{3+}$ ion has garnered significant interest due to its effectiveness in boosting the optical properties of host materials. Among the interesting phenomena is the commonly observed dual-band emission, which has often been interpreted by adopting the phenomenological model that explains the dual-band emission (ultraviolet band'' and visible band’’) in Sb-doped $ L$ PO$ _{4}$ ($ L$ = Sc, Y, Lu). However, the model for Sb-doped $ L$ PO$ _{4}$ series itself has not been well understood theoretically. In this work, we employ first-principles calculations combined with group-theory analysis to clarify the underlying physical mechanism behind dual-band emission in Sb-doped $ L$ PO$ _{4}$ series. We demonstrate that the dual-band arises from two excited-state equilibrium structures, one exhibits a relatively small distortion with respect to the ground-state equilibrium structure, while the other displays a significantly larger distortion, characteristic of an ``off-center’’ configuration. The deviations from the ground-state configuration are dominated by two distinct vibrational modes, $ b_2$ and $ e$ modes, involving the Jahn-Teller effect and the pseudo Jahn-Teller effect, respectively. Furthermore, charge transition levels and energy barriers calculated using the climbing image nudged elastic band (CI-NEB) method have aided in understanding the relaxation between the two excited-state configurations and the property changes across the Sc, Y, and Lu series. These insights provide a basis for understanding the exotic properties of Sb$ ^{3+}$ in other hosts and may facilitate the design of optical materials in a broader range of systems involving Sb$ ^{3+}$ ions.
Materials Science (cond-mat.mtrl-sci)
Nagaoka ferromagnetism in semiconductor artificial graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-03 20:00 EDT
Gökhan Öztarhan, Paweł Potasz, A. D. Güçlü
We present the emergence of Nagaoka ferromagnetism in semiconductor-based artificial graphene using high-precision variational and diffusion Monte Carlo methods, complemented by exact diagonalization calculations of the extended Hubbard model. Specifically, we analyze a realistic model of an armchair hexagonal geometry comprising $ 42$ lattice sites, nanopatterned on GaAs quantum wells with nearest-neighbor distance of $ a = 50$ nm. Our results reveal a distinct magnetic phase transition near $ U/t \approx 60$ driven by the absence/addition of a single electron at half-filling where the ferromagnetic phase is further stabilized by Coulomb scattering terms.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 5 figures, supplemental materials available
In-situ compression and shape recovery of Ceramic single grain micro-pillar
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Most ceramic materials are known for high fracture toughness while reacting highly brittle to physical deformation. Some advancements were made by utilizing the transformation toughening effect of Yttria-doped Zirconia. However, finding a ceramic material demonstrating an effect analogous to the Shape Memory Effect (SME) in certain metals, that also allows for superelastic responses, remains a challenge. The underlying mechanism for SME and superelasticity is based on crystallographic variations within the material’s grains, requiring sophisticated electron microscopy techniques for direct observation. The combination of a scanning electron microscope (SEM) with focused ion beam (FIB) milling, a Kleindiek Nanotechnik GmbH micro-manipulator with a 1.5 $ \mu$ m diamond tip, and the ability to achieve in-situ heating up to 450 °C on a Kleindiek heating stage provides a robust platform for the preparation, deformation, and heating of micro-pillars made from ceramic materials. This setup enabled us to conduct detailed studies on the Zirconia-based ceramic, observing permanent deformation exceeding 4% strain, followed by shape recovery at 370 °C. The paper provides outlines the key experimental steps that facilitated these observations.
Materials Science (cond-mat.mtrl-sci)
Surface forces and frictional properties of adsorbed bio-based cationic polysaccharide thin films in salted aqueous medium
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-03 20:00 EDT
Lionel Bureau, Simon Trouille, Gustavo S Luengo
Inter-surface forces mediated by polymer films are important in a range of technological and industrial situations. In cosmetics, applications such as hair conditioning typically rely on the adsorption of polyelectrolyte films onto the charged surface of hair fibers, whose contact mechanics and tribological properties are central in determining the final sensorial perceptions associated with the cosmetic treatment. A major current challenge to be tackled by the cosmetic industry is to design high-performance products employing bio-sourced polyelectrolytes, with the aim of achieving eco-sustainable processes and products. In this context, the present study focuses on the mechanical properties of thin films obtained by adsorption from solution of fungal chitosan onto negatively charged mica surfaces. We use a Surface Forces Apparatus allowing for the simultaneous measurement of film thickness and friction force as a function of the applied normal load and shear velocity. We show that, in aqueous medium at an ionic strength of 40 mM, adsorbed films of chitosan give rise to repulsive inter-surface forces whose range, comparable to the Flory radius of the macromolecules, increases with the polymer molecular weight. In addition, the adsorbed layers are found to behave, under compressive forces, as pseudo-brushes of neutral polymers. Finally, we show that under shear forces, chitosan layers exhibit a transition from a low to a high friction regime under increasing confinement.
Soft Condensed Matter (cond-mat.soft)
Laser Annealing of Transparent ZnO Thin Films: A Route to Improve Electrical Conductivity and Oxygen Sensing Capabilities
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
A. Frechilla, J. Frechilla, L. A. Angurel, F. Toldra-Reig, E. Martinez, G. F. de La Fuente, D. Munoz-Rojas
The chemical deposition of high-performance Zinc Oxide (ZnO) thin films is challenging, thus significant efforts have been devoted during the past decades to develop cost-effective, scalable fabrication methods in gas phase. This work demonstrates how ultra-short-pulse Laser Beam Scanning (LBS) can be used to modulate electrical conductivity in ZnO thin films deposited on soda-lime glass by Spatial Atomic Layer Deposition (SALD), a high-throughput, low-temperature deposition technique suitable for large-area applications. By systematically optimizing laser parameters, including pulse energy and hatching distance, significant improvements in the electrical performance of 90 nm-thick ZnO films were achieved. The optimization of the laser annealing parameters, 0.21 uJ/pulse energy and a 1 micron hatching distance, yielded ZnO films with an electrical resistivity of (9 +- 2) 10-2 Ohm cm, 3 orders of magnitude lower than as deposited films. This result suggests that laser post-deposition-processing can play an important role in tailoring the properties of ZnO thin films. Excessive laser intensity can compromise structural integrity of the films, however, degrading their electrical transport properties. Notably, the electrical resistance of laser-annealed ZnO films exhibited high sensitivity to oxygen concentration in the surrounding atmosphere, suggesting exciting prospects for application in devices based on transparent oxygen sensors. This study thus positions ultra-short pulsed laser annealing as a versatile post-deposition method for fine-tuning the properties of ZnO thin films, enabling their use in advanced optoelectronic and gas-sensing technologies, particularly on temperature-sensitive substrates.
Materials Science (cond-mat.mtrl-sci)
21 pages of Main Article plus Supplementary Information
Accelerating the discovery of high-performance nonlinear optical materials using active learning and high-throughput screening
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Victor Trinquet, Matthew L. Evans, Gian-Marco Rignanese
Due to their abundant use in all-solid-state lasers, nonlinear optical (NLO) crystals are needed for many applications across diverse fields such as medicine and communication. However, because of conflicting requirements, the design of suitable inorganic crystals with strong second-harmonic generation (SHG) has proven to be challenging to both experimentalists and computational scientists. In this work, we leverage a data-driven approach to accelerate the search for high-performance NLO materials. We construct an extensive pool of candidates using databases within the OPTIMADE federation and employ an active learning strategy to gather optimal data while iteratively improving a machine learning model. The result is a publicly accessible dataset of $ \sim$ 2,200 computed SHG tensors using density-functional perturbation theory. We further assess the performance of machine learning models on SHG prediction and introduce a multi-fidelity correction-learning scheme to refine data accuracy. This study represents a significant step towards data-driven materials discovery in the NLO field and demonstrates how new materials can be screened in an automated fashion.
Materials Science (cond-mat.mtrl-sci)
Ab-initio investigation of transition metal dichalcogenides for the hydrogenation of carbon dioxide to methanol
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Avaneesh Balasubramanian, Pawan Kumar Jha, Kaustubh Kaluskar, Sharan Shetty, Gopalakrishnan Sai Gautam
We computationally investigate the catalytic potential of MoSe$ _2$ , WS$ _2$ , and WSe$ _2$ nanoribbons and nanosheets for the partial hydrogenation of CO$ _2$ to methanol by comparing their electronic, adsorption, and defect properties to MoS$ _2$ , a known thermo-catalyst. We identify Se-deficient MoSe$ _2$ (followed by WSe$ _2$ ) nanosheets to be favorable for selective methanol formation.
Materials Science (cond-mat.mtrl-sci)
Fully ergodic simulations using radial updates
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Finn L. Temmen, Evan Berkowitz, Anthony Kennedy, Thomas Luu, Johann Ostmeyer, Xinhao Yu
A sensible application of the Hybrid Monte Carlo (HMC) method is often hindered by the presence of large - or even infinite - potential barriers. These potential barriers separate the configuration space into distinct sectors and can lead to ergodicity violations that bias measurements. In this work, we address this problem by augmenting HMC with a multiplicative Metropolis-Hastings update in a so-called ‘’radial direction’’ of the fields which enables crossing the potential barriers and ensures ergodicity of the sampling algorithm at comparably low computational cost. We demonstrate the algorithm on a simple toy model and show how it can be applied to the fermionic Hubbard model describing physics ranging from an exactly-solvable two-site system to the $ C_{20}H_{12}$ perylene molecule. Our numerical results show that the radial updates successfully remove ergodicity violations, while simultaneously reducing autocorrelation times.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Lattice (hep-lat)
19 pages, 13 figures
Strong Nonlinear Flexoelectricity in Bulk Ferroelectrics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Yingzhuo Lun, Yida Yang, Tingjun Wang, Qi Ren, Sang-Wook Cheong, Xueyun Wang, Jiawang Hong
Flexoelectricity induced by strain gradient in dielectrics is highly desirable for electromechanical actuating and sensing systems. It is broadly adopted that flexoelectric polarization responds linearly to strain gradient without considering nonlinearity. Consequently, the implication of nonlinear flexoelectricity in electromechanical systems remains unclear. Herein, we establish a nonlinear constitutive model for flexoelectricity and thereby propose a strategy for quantitatively measuring its nonlinearity through the high-order harmonic generations. A strong nonlinear flexoelectricity in bulk ferroelectrics is revealed and its coefficient is determined, as evidenced by their nonlinear dependence of harmonics on strain gradient. On this basis, we illustrate the nonlinear flexoelectricity manifests a functionality to transduce mixed mechanical excitations into coherent electrical signals featuring difference- and sum-frequencies, thereby offering utilization in signal processing for frequency conversion. These findings emphasize the significance of nonlinear flexoelectricity in ferroelectrics and open up new opportunities for designing electromechanical transducer based on nonlinear flexoelectricity.
Materials Science (cond-mat.mtrl-sci)
Shape transitions of sedimenting confined droplets and capsules: from oblate to bullet-like geometries
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-03 20:00 EDT
Danilo P. F. Silva, Rodrigo C. V. Coelho, Ariel Dvir, Noa Zana, Margarida M. Telo da Gama, Naomi Oppenheimer, Nuno A. M. Araujo
The transport and deformation of confined droplets and flexible capsules are central to diverse phenomena and applications, from biological flows in microcapillaries to industrial processes in porous media. We combine experiments and numerical simulations to investigate their shape dynamics under varying levels of confinement and particle flexibility. A transition from an oblate to a bullet-like shape is observed at a confinement threshold, independent of flexibility. A fluid-structure interaction analysis reveals two regimes: a pressure-dominated and a viscous-dominated regime. For highly flexible particles, the pressure-dominated regime prevails and the deformation is enhanced. These findings offer new insights into the transport of flexible particles in confined environments, with implications for biomedical applications, filtration technologies, and multiphase fluid mechanics.
Soft Condensed Matter (cond-mat.soft)
Higher-order topological phases for time-reversal-symmetry breaking superconductivity in UTe$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-03 20:00 EDT
Yuki Yamazaki, Shingo Kobayashi
The recent discovery of heavy-fermion superconductor UTe$ 2$ has broadened the possibility of realizing exotic time-reversal-symmetry-breaking superconductivity. However, a comprehensive understanding of the topological phases in the superconducting states of UTe$ 2$ is still lacking. Here, we present an exhaustive classification of topological phases for all time-reversal symmetry breaking pairing symmetries of UTe$ 2$ . Using the K theoretical classification approach, we uncover that 25 out of 36 possible pairing states are classified as higher-order topological phases, with some demonstrating hybrid-order topology through an intricate interplay of hinge and corner states. Furthermore, under the weak-coupling condition of the pair potentials, the possible pairing symmetries are constrained to $ B{ju} + i B{ku}$ , $ A{u} + i B_{j u}$ , and $ B_{j g} + iA_u$ ($ j,k = 1,2,3$ ; $ j \neq k$ ), where these symbols denote the irreducible representations of the point group $ D_{2h}$ . For these pairing states, the topological invariants are related to the Fermi surface topology via the Fermi-surface formula, enabling us to systematically diagnose higher-order topological phases. Using a tight-binding model, we demonstrate the higher-order topological phases of the mixed-parity $ A_u + iB_{1g}$ superconductors, where the second-order and hybrid-order topological phases emerge as the number of Fermi surfaces enclosing the time-reversal invariant momentum evolves from two to four. The findings suggest that UTe$ _2$ serves as a compelling platform for exploring higher-order topological superconductors with diverse topological surface states.
Superconductivity (cond-mat.supr-con)
26 pages, 7 figures
KTaO3(001) Preparation Methods in Vacuum: Effects on Surface Stoichiometry, Crystallography, and in-gap States
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Andrea M. Lucero Manzano, Esteban D. Cantero, Emanuel A. Martínez, F. Y. Bruno, Esteban A. Sánchez, Oscar Grizzi
KTaO3 single crystals with different orientations are used as substrates for the epitaxial growth of thin films and/or as hosts for two-dimensional electron gases. Due to the polar nature of the KTaO3(001) surface, one can expect difficulties and challenges to arise in its preparation. Maintaining good insulating characteristics without adding undesirable in-gap electronic states, obtaining good crystalline order up to the top surface layer, a sufficiently flat surface, and complete cleanliness of the surface (without water, C or OH contaminants), are in general difficult conditions to accomplish simultaneously. Cleaving in vacuum is likely the best option for obtaining a clean surface. However, since KTaO3 is cubic and lacks a well-defined cleavage plane, this method is notsuitable for sample growth or reproducible device fabrication. Here, we systematically evaluate the effect of typical preparation methods applied on the surfaces of KTaO3(001) single crystals. In particular, we used annealing in vacuum at different temperatures, light sputtering with Ar+ ions at low energy (500 eV) followed by annealing, heavy Ar+ ion bombardment and annealing, and grazing Ar+ ion bombardment under continuous azimuthal rotation combined with both annealing in vacuum and in O2 atmosphere. Possible side effects after each treatment are evaluated by a combination of techniques, including low-energy ion scattering at forward angles, Auger electron spectroscopy, low-energy electron energy loss, X-ray photoelectron spectroscopy, low-energy electron diffraction, and time of flightsecondary ion mass spectrometry. Advantages and shortcomings of each preparation method are discussed in detail.
Materials Science (cond-mat.mtrl-sci)
28 pages, 8 figures
Expanding the Horizons of Phase Transition-Based Luminescence Thermometry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
M. Tahir Abbas, M. Szymczak, V. Kinzhybalo, D. Szymanski, M. Drozd, L. Marciniak
The limited operational range of phase transition-based luminescence thermometers necessitates the exploration of new host materials exhibiting first-order structural phase transitions to broaden the applicability of this approach. Addressing this need, the present study investigates the spectroscopic properties of as a function of temperature. A thermally induced structural transition from the low-temperature orthorhombic phase to the high-temperature trigonal phase, occurring at approximately 430 K, significantly alters the spectroscopic properties of Eu3 ions. Specifically, a reduction in the number of Stark lines due to changes in the point symmetry of Eu3 ions enables the development of a ratiometric luminescence thermometer with sensitivity as high as K. Furthermore, it was demonstrated that increasing the concentration of Eu3 ions shifts the phase transition temperature, allowing for modulation of the thermometric performance of this luminescence thermometer. The findings presented here not only expand the repertoire of phase transition-based luminescence thermometers but also illustrate how the luminescence properties of Eu3 ions can be employed to accurately monitor structural changes in the host material.
Materials Science (cond-mat.mtrl-sci)
High-Chern-number Quantum anomalous Hall insulators in mixing-stacked MnBi$_2$Te$_4$ thin films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Jiaheng Li, Quansheng Wu, Hongming Weng
Quantum anomalous Hall (QAH) insulators are characterized by vanishing longitudinal resistance and quantized Hall resistance in the absence of an external magnetic field. Among them, high-Chern-number QAH insulators offer multiple nondissipative current channels, making them crucial for the development of low-power-consumption electronics. Using first-principles calculations, we propose that high-Chern-number ($ C>1$ ) QAH insulators can be realized in MnBi$ _2$ Te$ _4$ (MBT) multilayer films through the combination of mixed stacking orders, eliminating the need for additional buffer layers. The underlying physical mechanism is validated by calculating real-space-resolved anomalous Hall conductivity (AHC). Local AHC is found to be predominantly located in regions with consecutive correct stacking orders, contributing to quasi-quantized AHC. Conversely, regions with consecutive incorrect stacking contribute minimally to the total AHC, which can be attributed to the varied interlayer coupling in different stacking configurations. Our work provides valuable insights into the design principle for achieving large Chern numbers, and highlights the role of stacking configurations in manipulating electronic and topological properties in MBT films and its derivatives.
Materials Science (cond-mat.mtrl-sci)
7 pages, 4 figures
NIR-to-NIR ratiometric and lifetime based luminescence thermometer on a structural phase transition in Na3Sc2(PO4)3:Yb3+
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Anam Javaid, Maja Szymczak, Malgorzata Kubicka, Justyna Zeler, Vasyl Kinzhybalo, Marek Drozd, Damian Szymanski, Lukasz Marciniak
The ratiometric approach is the most commonly employed readout technique in luminescence thermometry. To address the trade-off between the risk of measurement disturbance in thermometers with high spectral separation of emission bands (due to dispersion in the surrounding medium) and the low sensitivity observed in ratiometric thermometers based on Stark level thermalization, we propose a thermometer based on the structural phase transition in . The use of Yb3+ ions as dopants and the changes in Stark level energies associated with the thermally induced monoclinic-to-trigonal phase transition enable the development of a thermometer with high relative sensitivity, achieving at 340K for N. Additionally, as demonstrated, the structural transition alters the probability of radiative depopulation of the 2F5/2 state of Yb3+, allowing the development of a lifetime-based luminescence thermometer. Furthermore, the phase transition temperature and consequently the thermometric performance of can be modulated by varying the Yb3+ ion concentration, offering additional tunability for specific applications.
Materials Science (cond-mat.mtrl-sci)
Shape Anisotropy Enabled Field Free Switching of Perpendicular Nanomagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-03 20:00 EDT
Akanksha Chouhan, Heston A. Mendonca, Abhishek Erram, Ashwin A. Tulapurkar
Spin Orbit Torque-Magnetic Random Access Memory (SOT-MRAM) is being developed as a successor to the Spin transfer torque MRAM (STT-MRAM) owing to its superior performance on the metrics of reliability and read-write speed. SOT switching of perpendicularly magnetized ferromagnet in the heavy metal/ferromagnet bilayer of SOT-MRAM unit cell requires an additional external magnetic field to support the spin-orbit torque generated by heavy metal to cause deterministic switching. This complexity can be overcome if an internal field can be generated to break the switching symmetry. We experimentally demonstrate that by engineering the shape of ferromagnet, an internal magnetic field capable of breaking the switching symmetry can be generated, which allows for deterministic switching by spin-orbit torques. We fabricated nanomagnets of Cobalt with triangular shape on top of Platinum and showed external magnetic field free switching between the two stable states of magnetization by application of nano-second voltage pulses. The experimental findings are consistent with the micro-magnetic simulation results of the proposed geometry.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Control of Andreev Reflection via a Single-Molecule Orbital
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-03 20:00 EDT
Lorenz Meyer, Jose L. Lado, Nicolas Néel, Jörg Kröger
Charge transport across a single-molecule junction fabricated from a normal-metal tip, a phthalocyanine, and a conventional superconductor in a scanning tunneling microscope is explored as a function of the gradually closed vacuum gap. The phthalocyanine (2H-Pc) molecule and its pyrrolichydrogen-abstracted derivative (Pc) exhibit vastly different behavior. Andreev reflection across the 2H-Pc contact exhibits a temporary enhancement that diminishes with increasing conductance. The hybridization of 2H-Pc with the tip at contact formation gives rise to a Kondo-screened molecular magnetic moment. In contrast, the single-Pc junction lacks Andreev reflection in the same conductance range. Spectroscopies and supporting nonequilibrium Green function calculations highlight the importance of a molecular orbital close to the Fermi energy for Andreev reflection.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
Controlling photo-excited electron-spin by light-polarization in ultrafast-pumped altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Amir Eskandari-asl, Jorge I. Facio, Oleg Janson, Adolfo Avella, Jeroen van den Brink
Altermagnets (AMs) constitute a novel class of spin-compensated materials in which the symmetry connecting opposite-spin sublattices involves a spatial rotation. Here, we uncover a set of unique non-linear, light-driven properties that set AMs apart from traditional ferro- and antiferromagnets. We demonstrate theoretically that the polarization of an electromagnetic pulse that photo-excites electrons and holes in an AM, controls the spin orientation of these non-equilibrium charge carriers. For a d-wave AM model and a prototype material, we show that very large post-pump spin polarizations may be attained by exploiting resonances. We show that this protocol also allows, in an AM, to directly probe the spin splitting of the electronic states in energy and momentum space. Thus, it can be used to identify and characterize altermagnetic materials via ultrafast pump-probe Kerr/Faraday spectroscopy or spin- and time-resolved ARPES. This opens up the possibility of devising ultrafast optical switches of non-equilibrium spin-polarization, finely tunable by adjusting the pump-pulse characteristics.
Materials Science (cond-mat.mtrl-sci)
Scaling in Magnetic Neutron Scattering
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-03 20:00 EDT
We report the discovery of scaling in the mesoscale magnetic microstructure of bulk ferromagnets. Supported by analytical micromagnetic theory, we introduce the field-dependent scaling length $ l_{\mathrm{C}}(H)$ , which describes the characteristic long-wavelength magnetization fluctuations that are caused by microstructural defects by means of magnetoelastic and magnetocrystalline anisotropy. The scaling length $ l_{\mathrm{C}}$ is identified to consist of the micromagnetic exchange length of the field $ l_{\mathrm{H}}$ , which depends on the magnetic interactions, and a field-independent contribution that reflects the properties of the magnetic anisotropy field and the magnetostatic fluctuations. The latter finding is rooted in the convolution relationship between the grain microstructure and micromagnetic response functions. We validated the scaling property by analyzing experimental data for the magnetic neutron scattering cross section. When plotted as a function of the dimensionless scaled scattering vector $ \mathfrak{q}(H) = q , l_{\mathrm{C}}(H)$ , the field-dependent amplitude-scaled neutron data of nanocrystalline Co and a Nd-Fe-B-based nanocomposite collapse onto a single master curve, demonstrating universal behavior. The scaling length $ l_{\mathrm{C}}$ provides a framework for analyzing the field-dependent neutron scattering cross section, highlighting the existence of critical length scales that govern the mesoscale microstructure of magnetic materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Introduction to dimensional reduction of fermions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Joel Hutchinson, Dmitry Miserev, Daniel Loss, Jelena Klinovaja
We present a comprehensive pedagogical introduction to the dimensional reduction protocol (DRP), a versatile framework for analyzing instabilities and critical points in interacting fermionic systems. The DRP simplifies the study of many-body problems by systematically reducing their effective spatial dimension while retaining essential physics. This method works for electron gases in a diverse array of settings: in any number of spatial dimensions, in the presence of Zeeman fields, with spin-orbit coupling, including repulsive or attractive interactions. Focusing on two-point correlation functions, the DRP identifies a minimal subspace relevant for capturing analytic properties, facilitating efficient computation of critical phenomena in electronic systems. This work outlines the assumptions, proof, and applications of the DRP, emphasizing its simplicity and broad applicability for future studies in correlated electron physics.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 10 figures
An anisotropic functional for two-dimensional material systems
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Density function theory is the workhorse of modern electronic structure theory. However, its accuracy in practical calculations is limited by the choice of the exchange-correlation potential. In this respect, 2D materials pose a special challenge, as all 2D materials and their heterostructures have a crucial similarity. The underlying atomic structures are strongly spatially inhomogeneous, implying that current exchange-correlation functionals, that in almost all cases are isotropic, are ill-prepared for an accurate description. We present an anisotropic screened-exchange potential, that remedies this problem and reproduces the band-gap of 2D materials as well as the piecewise linearity of the total energy with fractional occupation number.
Materials Science (cond-mat.mtrl-sci)
Toroid, Altermagnetic and Noncentrosymmetric ordering in metals
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
The article is dedicated to the 60th anniversary of the Landau Institute for Theoretical Physics and is a review of normal and superconducting properties of toroidal, altermagnetic and noncentrosymmetric metals. Metals with toroidal order are compounds with an electron spectrum that is asymmetric with respect to the reflection of the momentum. An electric current propagating through samples of such a material causes its magnetization. Superconducting states in toroidal metals are a mixture of singlet and triplet pair states. Superconductivity is gapless even in ideal crystals without impurities. Altermegnets are antiferromagnetic metals that have a specific splitting of electron bands determined by symmetry. In this respect, they are similar to metals whose symmetry does not have a spatial inversion operation. Both of these types of materials have an anomalous Hall effect. A current propagating through a noncentrosymmetric metal causes magnetization, but this is not the case in altermagnets. On the other hand, in altermagnets there is a specific piezomagnetic Hall effect. Superconducting pairing in non-centrosymmetric metals occurs between electrons occupying states in one zone, whereas in altermagnets we are dealing with interband pairing, which is unfavorable for the formation of a superconducting state.
Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 2 Figures, The article is dedicated to the 60th anniversary of the Landau Institute for Theoretical Physics. arXiv admin note: text overlap with arXiv:2412.05875
How chiral vibrations drive molecular rotation
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-03 20:00 EDT
Ivan Pasqua, Gregorio Staffieri, Michele Fabrizio
We analyze two simple model planar molecules: an ionic molecule with D3 symmetry and a covalent molecule with D6 symmetry. Both symmetries allow the existence of chiral molecular orbitals and normal modes that are coupled to each other in a Jahn-Teller manner, invariant under U (1) symmetry with generator a pseudo angular momentum. In the ionic molecule, the chiral mode possesses an electric dipole but lacks physical angular momentum, whereas, in the covalent molecule, the situation is reversed. In spite of that, we show that in both cases the chiral modes can be excited by a circularly polarized light and are subsequently able to induce rotational motion of the entire molecule. We further discuss the potential extension of our findings to the case of crystalline bulk samples.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
The protein escape process at the ribosomal exit tunnel has conserved mechanisms across the domains of life
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-03 20:00 EDT
Phuong Thuy Bui, Trinh Xuan Hoang
The ribosomal exit tunnel is the primary structure affecting the release of nascent proteins at the ribosome. The ribosomal exit tunnels from different species have elements of conservation and differentiation in structural and physico-chemical properties. In this study, by simulating the elongation and escape processes of nascent proteins at the ribosomal exit tunnels of four different organisms, we show that the escape process has conserved mechanisms across the domains of life. Specifically, it is found that the escape process of proteins follows the diffusion mechanism given by a simple diffusion model and the median escape time positively correlates with the number of hydrophobic residues and the net charge of a protein for all the exit tunnels considered. These properties hold for twelve distinct proteins considered in two slightly different and improved Gō-like models. It is also found that the differences in physico-chemical properties of the tunnels lead to quantitative differences in the protein escape times. In particular, the relatively strong hydrophobicity of the E. coli’s tunnel and the unusually high number of negatively charged amino acids on the tunnel’s surface of H. marismortui lead to substantially slower escapes of proteins at these tunnels than at those of S. cerevisisae and H. sapiens.
Soft Condensed Matter (cond-mat.soft)
11 pages, 5 figures, supplementary material
J. Chem. Phys. 158, 015102 (2023)
High-Yield Assembly of Plasmon-Coupled Nanodiamonds \textit{via} DNA Origami for Tailored Emission
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Niklas Hansen, Jakub Copak, Marek Kindermann, David Roesel, Federica Scollo, Ilko Bald, Petr Cigler, Vladimira Petrakova
Controlling the spatial arrangement of optically active elements is crucial for the advancement of engineered photonic systems. Color centers in nanodiamond offer unique advantages for quantum sensing and information processing; however, their integration into complex optical architectures is limited by challenges in precise and reproducible positioning, as well as efficient coupling. DNA origami provides an elegant solution, as demonstrated by recent studies showcasing nanoscale positioning of fluorescent nanodiamonds and plasmonic gold nanoparticles. Here, we present a scalable and robust method for covalently functionalizing nanodiamonds with DNA, enabling high-yield, spatially controlled assembly of diamond and gold nanoparticles onto DNA origami. By precisely controlling the interparticle spacing, we reveal distance-dependent modulation of NV center photoluminescence with a 10-fold increase in the fastest decay pathway at short interparticle distances. Our findings indicate selective plasmon-driven effects and interplay between radiative and non-radiative processes. This work overcomes key limitations in current nanodiamond assembly strategies and provides insights into engineering NV photoluminescence by plasmonic coupling that advance toward quantum photonic and sensing applications.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Fully-gapped superconductivity with rotational symmetry breaking in pressurized kagome metal CsV$_3$Sb$_5$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-03 20:00 EDT
X. Y. Feng, Z. Zhao, J. Luo, Y. Z. Zhou, J. Yang, A. F. Fang, H. T. Yang, H.-J. Gao, R. Zhou, Guo-qing Zheng
The discovery of the kagome metal CsV$ 3$ Sb$ 5$ has generated significant interest in its complex physical properties, particularly its superconducting behavior under different pressures, though its nature remains debated. Here, we performed low-temperature, high-pressure $ ^{121/123}$ Sb nuclear quadrupole resonance (NQR) measurements to explore the superconducting pairing symmetry in CsV$ 3$ Sb$ 5$ . At ambient pressure, we found that the spin-lattice relaxation rate 1/$ T_1$ exhibits a kink at $ T \sim$ 0.4 $ T\textrm{c}$ within the superconducting state and follows a $ T^3$ variation as temperature further decreases. This suggests the presence of two superconducting gaps with line nodes in the smaller one. As pressure increases beyond $ P{\rm c} \sim 1.85$ GPa, where the charge-density wave phase is completely suppressed, 1/$ T_1$ shows no Hebel-Slichter peak just below $ T\textrm{c}$ , and decreases rapidly, even faster than $ T^5$ , indicating that the gap is fully opened for pressures above $ P{\rm c}$ . In this high pressure region, the angular dependence of the in-plane upper critical magnetic field $ H_{\rm c2}$ breaks the $ C_6$ rotational symmetry. We propose the $ s+id$ pairing at $ P > P_{\rm c}$ which explains both the 1/$ T_1$ and $ H_{\rm c2}$ behaviors. Our findings indicate that CsV$ _3$ Sb$ _5$ is an unconventional superconductor and its superconducting state is even more exotic at high pressures.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
25 pages, 4 figures, to appear in Nature Communications
A quantitative theory and atomistic simulation study on the soft-sphere crystal-melt interfacial properties: II. Interfacial free energies
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Ya-Shen Wang, Zun Liang, Brian B. Laird, Yang Yang
This study proposes a new method for predicting the crystal-melt interfacial free energy ($ \gamma$ ) using the Ginzburg-Landau (GL) model, enhanced by atomistic simulation data for more accurate density wave profiles. The analysis focuses on the soft-sphere system governed by an inverse power potential that stabilizes both BCC and FCC phases. Equilibrium molecular dynamics (MD) simulations are used to obtain density wave amplitude distributions, which serve as inputs for the GL model to predict $ \gamma$ and its anisotropy. The predicted $ \gamma$ values exhibit strong agreement with prior benchmark simulation experimental studies, particularly for FCC crystal-melt interfaces (CMIs). The GL models for the CMI $ \gamma$ are proved to be both computationally efficient and reasonably valid, offering quantitative predictions of $ \gamma$ while providing insights into the factors controlling its magnitude and anisotropy. Key improvement is suggested for the variational procedure used in the two-mode CMI free energy functionals, and potential upgrades to the GL model are also proposed to further enhance predictive accuracy.
Materials Science (cond-mat.mtrl-sci)
12 pages, 5 figures
How to Reliably Measure Carrier Mobility in Highly Resistive Lead Halide Perovskites with Photo-Hall Experiment
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Soumen Kundu, Yeswanth Pattipati, Krishnamachari Lakshmi Narasimhan, Sushobhan Avasthi
Mobility measurements in highly resistive methylammonium lead iodide (MAPI) are challenging due to high impedance, ion drift, and low mobility. We show that we can address the challenge using intensity-dependent photo-Hall measurements. The key is an improved photo-Hall setup, which enables reliable Hall measurements in the dark and under low-intensity illumination. By tuning the illumination over four orders of magnitude, we get the additional information to simultaneously extract hole mobility, electron mobility, and background doping. For the first time, we show that a MAPI single crystal, exhibiting n-type behaviour in the dark, can show p-type behaviour under light due to the difference in hole and electron mobility. The data partly explains the variability in mobility reported in the literature. We show that one can erroneously extract any mobility from 0 to 25 cm2/Vs if we restrict the experiment to a small range of illumination intensities. For our MAPI (310) crystal, the measured hole and electron mobility is 40 cm2/Vs and 25.5 cm2/Vs, respectively.
Materials Science (cond-mat.mtrl-sci)
45 pages (including supplementary) 4 main figures, 16 supplementary figures
Topological Feature of Real-time Fisher Zeros
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Yuchen Meng, Yang Liu, Erhai Zhao, Haiyuan Zou
There are numerous methods to characterize topology and its boundary zero modes, yet their statistical mechanical properties have not received as much attention as other approaches. Here, we investigate the Fisher zeros and thermofield dynamics of topological models, revealing that boundary zero modes can be described by an overlooked real-time Fisher zero pairing effect. This effect is validated in the Su-Schrieffer-Heeger model and the Kitaev chain model, with the latter exhibiting a Fisher zero braiding picture. Topological zero modes exhibit robustness even when non-Hermiticity is introduced into the system and display characteristics of imaginary-time crystals when the energy eigenvalues are complex. We further examine the real-time Fisher zeros of the one-dimensional transverse field Ising model, which maps to the Kitaev chain. We present a fractal picture of the Fisher zeros, illustrating how interactions eliminate topology. The mechanism of zero-pairing provides a natural statistical mechanical approach to understanding the connection between topology and many-body physics.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Lattice (hep-lat), Quantum Physics (quant-ph)
6 pages, 4 figures
A method to derive material-specific spin-bath model descriptions of materials displaying prevalent spin physics (for simulation on NISQ devices)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-04-03 20:00 EDT
Benedikt M. Schoenauer, Nicklas Enenkel, Florian G. Eich, Vladimir V. Rybkin, Michael Marthaler, Sebastian Zanker, Peter Schmitteckert
Magnetism and spin physics are true quantum mechanical effects and their description usually requires multi reference methods and is often hidden in the standard description of molecules in quantum chemistry. In this work we present a twofold approach to the description of spin physics in molecules and solids. First, we present a method that identifies the single-particle basis in which a given subset of the orbitals is equivalent to spin degrees of freedom for models and materials which feature significant spin physics at low energies. We introduce a metric for the spin-like character of a basis orbital, of which the optimization yields the basis containing the optimum spin-like basis orbitals. Second, we demonstrate an extended Schrieffer-Wolff transformation method to derive the effective Hamiltonian acting on the subspace of the Hilbert space in which the charge degree of freedom of electron densities in the spin-like orbitals is integrated out. The method then yields an effective spin-bath Hamiltonian description for the system. This extended Schrieffer-Wolff transformation is applicable to a wide range of Hamiltonians and has been utilized in this work for model Hamiltonians as well as the active space Hamiltonian of molecular chromium bromide.
Strongly Correlated Electrons (cond-mat.str-el)
17 pages, 8 figures
Effects of Dynamic Bonds on the Kinetic Pathways of Supramolecular Diblock Copolymers Disorder-Order Transition
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-04-03 20:00 EDT
Supramolecular block copolymers (SBC) consist of covalent polymer building blocks that are connected into well-defined architectures via supramolecular bonds. Assisted by the dynamic and reversible supramolecular interactions, it is envisaged that SBC self-assemblies may exhibit more diverse morphologies, stimuli-responsivity comparing to their covalent analogues. At the fundamental level, these features are related to the free-energy landscape of self-assemblies. It is therefore of central importance to understand the impact of dynamic/reversible bonds on the free energy landscape during structure transitions. In this study, we first conduct smart Monte Carlo simulations to compare the kinetics of the disorder-order transition (DOT) of supramolecular diblock copolymers (SDBC) to that of covalent diblock copolymers (CDBC). The structural order parameter for CDBC exhibits a fast and smooth transition process across different random number seeds and initial configurations. In contrast, the SDBC system shows more diverse transition pathways, which can be classified into three types. These results suggest that reversible supramolecular interactions complicate the pathways, and bring about various intermediate structures. Next, we apply the string method to construct the minimum free energy path of the transition, from which the transition state and the free energy barrier are evaluated. It is found that the transition free energy barrier strongly correlates with the fraction of supramolecules. By decomposing the free energy into A-B interaction energy and association energy, we found that the interplay of both two effects decide the kinetic pathway and the final equilibrium structures.
Soft Condensed Matter (cond-mat.soft)
Partition function zeros of quantum many-body systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-04-03 20:00 EDT
We present a method for calculating the Yang-Lee partition function zeros of a translationally invariant model of lattice fermions, exemplified by the Hubbard model. The method rests on a theorem involving the single electron self-energy $ \Sigma_\sigma(k, i \omega_n)$ in the imaginary time Matsubara formulation. The theorem maps the Yang-Lee zeros to a set of wavevector and spin labeled virtual energies $ \xi_{k \sigma}$ . These, thermodynamically derived virtual energies, are solutions of equations involving the self-energy at corresponding $ k\sigma$ ‘s. Examples of the method in simplified situations are provided.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
32 pages, 4 figures
Thermoelectric AC Josephson effect
New Submission | Superconductivity (cond-mat.supr-con) | 2025-04-03 20:00 EDT
Olli Mansikkamäki, Francesco Giazotto, Alexander Balatsky
A temperature gradient $ {\Delta}T$ across a Josephson junction induces a thermoelectric current. We predict the AC Josephson effect is activated when this current surpasses the junction’s critical current. Our investigation of this phenomenon employs the time-dependent Ginzburg-Landau theory framework in proximity to the critical temperature. Our results indicate that the frequency of the AC current is approximately given by $ {\pi} S {\Delta} T / (2 {\Phi}_0)$ , where $ S$ represents the Seebeck coefficient and $ {\Phi}_0$ the magnetic flux quantum and we estimate the frequency be on the range of GHz for Sn up to a THz for larger $ S$ and $ T_c$ materials. Furthermore, we propose two distinct experimental configurations to observe this effect.
Superconductivity (cond-mat.supr-con)
Observing Spatial Charge and Spin Correlations in a Strongly-Interacting Fermi Gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-04-03 20:00 EDT
Cyprien Daix, Maxime Dixmerias, Yuan-Yao He, Joris Verstraten, Tim de Jongh, Bruno Peaudecerf, Shiwei Zhang, Tarik Yefsah
Two-dimensional correlated fermions constitute a cornerstone of quantum matter, covering a broad fundamental and technological scope, and have attracted increasing interest with the emergence of modern materials such as high-$ T_{\rm c}$ superconductors, graphene, topological insulators, and Moiré structures. Atom-based quantum simulators provide a new pathway to understand the microscopic mechanisms occurring at the heart of such systems. In this work, we explore two-dimensional attractive Fermi gases at the microscopic level by probing spatial charge and spin correlations in situ. Using atom-resolved continuum quantum gas microscopy, we directly observe fermion pairing and study the evolution of two- and three-point correlation functions as inter-spin attraction is increased. The precision of our measurement allows us to reveal a marked dip in the pair correlation function, fundamentally forbidden by the mean-field result based on Bardeen-Cooper-Schrieffer (BCS) theory but whose existence we confirm in exact auxiliary-field quantum Monte Carlo calculations. We demonstrate that the BCS prediction is critically deficient not only in the superfluid crossover regime but also deep in the weakly attractive side. Guided by our measurements, we find a remarkable relation between two- and three-point correlations that establishes the dominant role of pair-correlations. Finally, leveraging local single-pair losses, we independently characterize the short-range behavior of pair correlations, via the measurement of Tan’s Contact, and find excellent agreement with numerical predictions. Our measurements provide an unprecedented microscopic view into two-dimensional Fermi gases and constitute a paradigm shift for future studies of strongly-correlated fermionic matter in the continuum.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
13 pages, 11 figures
Composition Design of Shape Memory Ceramics based on Gaussian Processes
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-04-03 20:00 EDT
Ashutosh Pandey, Justin Jetter, Hanlin Gu, Eckhard Quandt, Richard D. James
We present a Gaussian process machine learning model to predict the transformation temperature and lattice parameters of ZrO$ _2$ -based ceramics. Our overall goal is to search for a shape memory ceramic with a reversible transformation and low hysteresis. The identification of a new low hysteresis composition is based on design criteria that have been successful in metal alloys: (1) $ \lambda_2 = 1$ , where $ \lambda_2$ is the middle eigenvalue of the transformation stretch tensor, (2) minimizing the max$ |q(f)|$ , which measures the deviation from satisfying the cofactor conditions, (3) high transformation temperature, (4) low transformational volume change, and (5) solid solubility. We generate many synthetic compositions, and identify a promising composition, 31.75Zr-37.75Hf-14.5Y-14.5Ta-1.5Er, which closely satisfies all the design criteria based on predictions from machine learning. However, differential thermal analysis reveals a relatively high thermal hysteresis of 137°C for this composition, indicating that the proposed design criteria are not universally applicable to all ZrO$ _2$ -based ceramics. We also explore reducing tetragonality of the austenite phase by addition of Er$ _2$ O$ _3$ . The idea is to tune the lattice parameters of austenite phase towards a cubic structure will increase the number of martensite variants, thus, allowing more flexibility for them to accommodate high strain during transformation. We find the effect of Er$ _2$ O$ _3$ on tetragonality is weak due to limited solubility. We conclude that a more effective dopant is needed to achieve significant tetragonality reduction. Overall, Gaussian process machine learning models are shown to be highly useful for prediction of compositions and lattice parameters, but the discovery of low hysteresis ceramic materials apparently involves other factors not relevant to phase transformations in metals.
Materials Science (cond-mat.mtrl-sci), Data Analysis, Statistics and Probability (physics.data-an)
24 pages article (28 pages including references), 11 figures, 4 tables
Sliding Dynamics of Skyrmion Molecular Crystals
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-04-03 20:00 EDT
J. C. Bellizotti Souza, C. J. O. Reichhardt, C. Reichhardt, N. P. Vizarim, P. A. Venegas
Using both atomistic and particle-based simulations, we investigate the current-driven dynamics of skyrmions on two-dimensional periodic substrates when there are multiple skyrmions per substrate minimum. At zero drive, the system forms pinned skyrmion molecular crystal states consisting of dimers, trimers, or dimer-trimer mixtures that have both positional and orientational order. On a square substrate lattice, the motion above depinning occurs via a running soliton that travels completely transverse to the applied current. This motion is generated by a torque from the Magnus force, which rotates the $ n$ -mer states perpendicular to the applied current. At higher drives, the flow becomes disordered while the Hall angle diminishes and gradually approaches the intrinsic value. In some cases, we also find directional locking where the Hall angle becomes locked to certain symmetry directions of the substrate over a range of currents. The transitions into and out of directionally locked states are accompanied by negative differential mobility in which the net velocity decreases as the drive increases. On a triangular substrate, we find no transverse mobility effects, but still observe directionally locked motion.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
26 pages, 20 figures