CMP Journal 2025-02-03
Statistics
Nature: 1
Nature Materials: 2
Nature Nanotechnology: 4
Nature Physics: 1
Physical Review Letters: 4
Physical Review X: 1
arXiv: 46
Nature
Left-right-alternating theta sweeps in entorhinal-hippocampal maps of space
Original Paper | Network models | 2025-02-02 19:00 EST
Abraham Z. Vollan, Richard J. Gardner, May-Britt Moser, Edvard I. Moser
Place cells in the hippocampus and grid cells in the entorhinal cortex are elements of a neural map of self position1,2,3,4,5. For these cells to benefit navigation, their representation must be dynamically related to the surrounding locations2. A candidate mechanism for linking places along an animal's path has been described for place cells, in which the sequence of spikes in each cycle of the hippocampal theta oscillation encodes a trajectory from the animal's current location towards upcoming locations6,7,8. In mazes that bifurcate, such trajectories alternately traverse the two upcoming arms when the animal approaches the choice point9,10, raising the possibility that the trajectories express available forward paths encoded on previous trials10. However, to bridge the animal's path with the wider environment, beyond places previously or subsequently visited, an experience-independent spatial sampling mechanism might be required. Here we show in freely moving rats that in individual theta cycles, ensembles of grid cells and place cells encode a position signal that sweeps linearly outwards from the animal's location into the ambient environment, with sweep direction alternating stereotypically between left and right across successive theta cycles. These sweeps are accompanied by, and aligned with, a similarly alternating directional signal in a discrete population of parasubiculum cells that have putative connections to grid cells via conjunctive grid × direction cells. Sweeps extend into never-visited locations that are inaccessible to the animal. Sweeps persist during REM sleep. The sweep directions can be explained by an algorithm that maximizes the cumulative coverage of the surrounding manifold space. The sustained and unconditional expression of theta-patterned left-right-alternating sweeps in the entorhinal-hippocampal positioning system provides an efficient ‘look around' mechanism for sampling locations beyond the travelled path.
Network models, Neural circuits
Nature Materials
Electroreduction-driven distorted nanotwins activate pure Cu for efficient hydrogen evolution
Original Paper | Electrocatalysis | 2025-02-02 19:00 EST
Zhe Li, Yueshuai Wang, Hui Liu, Yi Feng, Xiwen Du, Zhiheng Xie, Jihan Zhou, Yang Liu, Yun Song, Fei Wang, Manling Sui, Yue Lu, Fang Fang, Dalin Sun
Precious metals such as Pt are favoured as catalysts for the hydrogen evolution reaction (HER) due to their excellent catalytic activity. However, the scarcity and high cost of precious metals have prompted researchers to explore cheaper alternatives such as Cu. Nevertheless, Cu shows poor catalytic performance due to weak binding with intermediates. Here the catalytic activity of pure Cu is activated via electroreduction-driven modification of the local structure, achieving a HER catalytic performance superior to commercial Pt/C catalysts for working current densities greater than 100 mA cm-2 in acid electrolyte. Activation involved two steps. First, polycrystalline Cu2O nanoparticles were prepared via pulsed laser ablation, resulting in grain boundaries within the Cu2O particles as observed using electron microscopy. Next, the Cu2O particles were electroreduced to pure Cu, inducing the formation of distorted nanotwins and edge dislocations. These local structures induce high lattice strain and decrease the Cu coordination number, enhancing the interaction between Cu and intermediates--as calculated using density functional theory--leading to the excellent catalytic activity and durability of the catalyst. Our observations show that low-cost pure Cu can be a promising HER catalyst for large-scale industrial applications.
Electrocatalysis, Nanoparticles
Printable molecule-selective core-shell nanoparticles for wearable and implantable sensing
Original Paper | Biomedical engineering | 2025-02-02 19:00 EST
Minqiang Wang, Cui Ye, Yiran Yang, Daniel Mukasa, Canran Wang, Changhao Xu, Jihong Min, Samuel A. Solomon, Jiaobing Tu, Guofang Shen, Songsong Tang, Tzung K. Hsiai, Zhaoping Li, Jeannine S. McCune, Wei Gao
Wearable and implantable biosensors are pioneering new frontiers in precision medicine by enabling continuous biomolecule analysis for fundamental investigation and personalized health monitoring. However, their widespread adoption remains impeded by challenges such as the limited number of detectable targets, operational instability and production scalability. Here, to address these issues, we introduce printable core-shell nanoparticles with built-in dual functionality: a molecularly imprinted polymer shell for customizable target recognition, and a nickel hexacyanoferrate core for stable electrochemical transduction. Using inkjet printing with an optimized nanoparticle ink formulation, we demonstrate the mass production of robust and flexible biosensors capable of continuously monitoring a broad spectrum of biomarkers, including amino acids, vitamins, metabolites and drugs. We demonstrate their effectiveness in wearable metabolic monitoring of vitamin C, tryptophan and creatinine in individuals with long COVID. Additionally, we validate their utility in therapeutic drug monitoring for cancer patients and in a mouse model through providing real-time analysis of immunosuppressants such as busulfan, cyclophosphamide and mycophenolic acid.
Biomedical engineering, Nanoscience and technology, Sensors, Sensors and biosensors
Nature Nanotechnology
Spin-torque-driven gigahertz magnetization dynamics in the non-collinear antiferromagnet Mn3Sn
Original Paper | Spintronics | 2025-02-02 19:00 EST
Won-Bin Lee, Seongmun Hwang, Hye-Won Ko, Byong-Guk Park, Kyung-Jin Lee, Gyung-Min Choi
Non-collinear antiferromagnets, such as Mn3Sn, stand out for their topological properties and potential in antiferromagnetic spintronics. This emerging field aims at harnessing ultrafast magnetization dynamics of antiferromagnets through spin torques. Here we report the time-resolved dynamics of Mn3Sn on a picosecond timescale, driven by an optically induced spin current pulse. Our results reveal that the magnetization of Mn3Sn tilts immediately after the spin current pulse and subsequently undergoes 70 GHz precession. This immediate tilting underscores the predominant role of damping-like torque stemming from spin current absorption by Mn3Sn. We also determine the spin coherence length of Mn3Sn to be approximately 15 nm. This value substantially exceeds that of ferromagnets, highlighting a distinct spin-dephasing process in non-collinear antiferromagnets. Our results hold promise for ultrafast applications of non-collinear antiferromagnets and enrich our understanding of their spin-transfer physics.
Spintronics
Nature-inspired platform nanotechnology for RNA delivery to myeloid cells and their bone marrow progenitors
Original Paper | Drug delivery | 2025-02-02 19:00 EST
Stijn R. J. Hofstraat, Tom Anbergen, Robby Zwolsman, Jeroen Deckers, Yuri van Elsas, Mirre M. Trines, Iris Versteeg, Daniek Hoorn, Gijs W. B. Ros, Branca M. Bartelet, Merel M. A. Hendrikx, Youssef B. Darwish, Teun Kleuskens, Francisca Borges, Rianne J. F. Maas, Lars M. Verhalle, Willem Tielemans, Pieter Vader, Olivier G. de Jong, Tommaso Tabaglio, Dave Keng Boon Wee, Abraham J. P. Teunissen, Eliane Brechbühl, Henk M. Janssen, P. Michel Fransen, Anne de Dreu, David P. Schrijver, Bram Priem, Yohana C. Toner, Thijs J. Beldman, Mihai G. Netea, Willem J. M. Mulder, Ewelina Kluza, Roy van der Meel
Nucleic acid therapeutics are used for silencing, expressing or editing genes in vivo. However, their systemic stability and targeted delivery to bone marrow resident cells remains a challenge. In this study we present a nanotechnology platform based on natural lipoproteins, designed for delivering small interfering RNA (siRNA), antisense oligonucleotides and messenger RNA to myeloid cells and haematopoietic stem and progenitor cells in the bone marrow. We developed a prototype apolipoprotein nanoparticle (aNP) that stably incorporates siRNA into its core. We then created a comprehensive library of aNP formulations and extensively characterized their physicochemical properties and in vitro performance. From this library, we selected eight representative aNP-siRNA formulations and evaluated their ability to silence lysosomal-associated membrane protein 1 (Lamp1) expression in immune cell subsets in mice after intravenous administration. Using the most effective aNP identified from the screening process, we tested the platform's potential for therapeutic gene silencing in a syngeneic murine tumour model. We also demonstrated the aNP platform's suitability for splice-switching with antisense oligonucleotides and for protein production with messenger RNA by myeloid progenitor cells in the bone marrow. Our data indicate that the aNP platform holds translational potential for delivering various types of nucleic acid therapeutics to myeloid cells and their progenitors.
Drug delivery, Nanoparticles
Resolving polarization switching pathways of sliding ferroelectricity in trilayer 3R-MoS2
Original Paper | Ferroelectrics and multiferroics | 2025-02-02 19:00 EST
Jing Liang, Dongyang Yang, Jingda Wu, Yunhuan Xiao, Kenji Watanabe, Takashi Taniguchi, Jerry I. Dadap, Ziliang Ye
Sliding ferroelectricity, an emerging type of hysteretic behaviour with strong potential for memory-related applications, involves dynamically switching the polarization associated with the stacking arrangement in two-dimensional van der Waals materials. Because different stacking configurations can share a degenerate net polarization, it has remained a challenge to resolve the intermediate stacking configuration and the polarization switching pathway in multi-interface devices. In this work, we present an optical approach to resolve the polarization degeneracy in a trilayer 3R-MoS2 over different switching cycles. By performing reflection contrast spectroscopy in dual-gated devices, we identify distinct responses of inter- and intralayer excitons in all four possible stacking configurations (ABC, ABA, BAB and CBA). Diffraction-limited spatial resolution makes it possible to image the switching of the stacking configurations. We find that the switching pathway is influenced not only by the competition among pinning centres--which localize domain walls at different interfaces--but also by a free-carrier screening effect linked to chemical doping. These findings highlight the importance of managing domain walls, pinning centres and doping levels in sliding ferroelectric devices, offering insights for further development in sensing and computing applications.
Ferroelectrics and multiferroics, Two-dimensional materials
Multivalent-effect immobilization of reduced-dimensional perovskites for efficient and spectrally stable deep-blue light-emitting diodes
Original Paper | Lasers, LEDs and light sources | 2025-02-02 19:00 EST
Jianchao Dong, Bin Zhao, Huiyu Ji, Ziang Zang, Lingmei Kong, Chunshuang Chu, Dongyuan Han, Jie Wang, Yuhao Fu, Zi-Hui Zhang, Yingguo Yang, Lijun Zhang, Xuyong Yang, Ning Wang
Despite substantial advances in green and red metal halide perovskite light-emitting diodes (PeLEDs), blue PeLEDs, particularly deep-blue ones (defined as Commission International de l'Eclairage y coordinate (CIEy) less than 0.06) that meet the latest Rec. 2020 colour gamut standard, lag dramatically behind owing to a severe phase segregation-induced electroluminescent spectral shift and low exciton utilization in broadened bandgap perovskite emitters. Here we propose a multivalent immobilization strategy to realize high-efficiency and spectrally stable deep-blue PeLEDs by introducing a polyfluorinated oxygen-containing molecule. Systematic experiments and extensive 5,000 fs ab initio molecular dynamics simulations reveal that a crucial role of the multivalent effect stemming from three kinds of interaction of hydrogen bond (F···H-N), ionic bond (F-Pb) and coordination bond (C=O:Pb) with perovskite is to synergistically stabilize the perovskite phase and enhance exciton radiative recombination. The resultant exciton concentration and exciton recombination rate of the deep-blue perovskite emitter are increased by factors of 1.66 and 1.64, respectively. In this context, our target PeLEDs demonstrate a peak external quantum efficiency of up to 15.36% at a deep-blue emission wavelength of 459 nm and a half-lifetime of 144 min at a constant current density of 0.45 mA cm-2. Moreover, the deep-blue PeLEDs maintain a constant spectrum peak with CIE chromaticity coordinates of (0.136, 0.051) under a steady driving current for 60 min.
Lasers, LEDs and light sources, Nanoscale devices
Nature Physics
Constraints on the location of the liquid-liquid critical point in water
Original Paper | Atomistic models | 2025-02-02 19:00 EST
F. Sciortino, Y. Zhai, S. L. Bore, F. Paesani
The fascinating hypothesis that supercooled water may segregate into two distinct liquid phases, each with unique structures and densities, was first posited in 1992. This idea, initially based on numerical analyses with the ST2 water-like empirical potential, challenged the conventional understanding of water's phase behaviour at the time and has since intrigued the scientific community. Over the past three decades, advancements in computational modelling--particularly through the advent of data-driven many-body potentials rigorously derived from first principles and augmented by the efficiency of neural networks--have greatly enhanced the accuracy of molecular simulations, enabling the exploration of the phase behaviour of water with unprecedented realism. Our study leverages these computational advances to probe the elusive liquid-liquid transition in supercooled water. Microsecond-long simulations with chemical accuracy, conducted over several years, provide compelling evidence that water indeed exists in two discernibly distinct liquid states at low temperature and high pressure. By pinpointing a realistic estimate for the location of the liquid-liquid critical point at ~198 K and ~1,250 atm, our study not only advances the current understanding of water's anomalous behaviour but also establishes a basis for experimental validation. Importantly, our simulations indicate that the liquid-liquid critical point falls within temperature and pressure ranges that could potentially be experimentally probed in water nanodroplets, opening up the possibility for direct measurements.
Atomistic models, Chemical physics, Phase transitions and critical phenomena, Statistical mechanics
Physical Review Letters
Solar Modulation of Cosmic Nuclei over a Solar Cycle: Results from the Alpha Magnetic Spectrometer
Research article | Cosmic ray composition & spectra | 2025-02-03 05:00 EST
M. Aguilar et al. (AMS Collaboration)
We report the properties of precision time structures of cosmic nuclei He, Li, Be, B, C, N, and O fluxes over an 11-year solar cycle from May 2011 to November 2022 in the rigidity range from 1.92 to 60.3 GV. The nuclei fluxes show similar but not identical time variations with amplitudes decreasing with increasing rigidity. In particular, below 3.64 GV the Li, Be, and B fluxes, and below 2.15 GV the C, N, and O fluxes, are significantly less affected by solar modulation than the He flux. We observe that these differences in solar modulation are linearly correlated with the differences in the spectral indices of the cosmic nuclei fluxes. This shows, in a model-independent way, that solar modulation of galactic cosmic nuclei depends on their spectral shape. In addition, solar modulation differences due to nuclei velocity dependence on the mass-to-charge ratio (\(A/Z\)) are not observed.
Phys. Rev. Lett. 134, 051001 (2025)
Cosmic ray composition & spectra, Cosmic ray propagation, Particle astrophysics
Antiprotons and Elementary Particles over a Solar Cycle: Results from the Alpha Magnetic Spectrometer
Research article | Cosmic ray composition & spectra | 2025-02-03 05:00 EST
M. Aguilar et al. (AMS Collaboration)
et al.The spectrum of cosmic-ray antiprotons has been measured for a full solar cycle, which may allow a better understanding of the sources and transport mechanisms of these high-energy particles.
Phys. Rev. Lett. 134, 051002 (2025)
Cosmic ray composition & spectra, Cosmic ray propagation, Cosmic ray sources, Particle astrophysics, Particle dark matter
Observation of Photonic Mobility Edge Phases
Research article | Integrated optics | 2025-02-03 05:00 EST
Yi-Jun Chang, Jia-Hui Zhang, Yong-Heng Lu, Ying-Yue Yang, Feng Mei, Jie Ma, Suotang Jia, and Xian-Min Jin
Inverse Anderson localizations in lower dimensions predict that, as the hopping rates increase, all localized eigenmodes transition to extended states. Here, through the implementation of a mosaic quasiperiodic photonic waveguide lattice, we experimentally demonstrate a distinctive scenario, where the intermediate-energy eigenmodes become extended, while the low- or high-energy eigenmodes remain localized, leading to the emergence of energy-dependent Anderson localization transitions and mobility edge phases. Our experiment is enabled by developing an adiabatic procedure to prepare the photonic lattice into the zero-energy, lower and upper middle-energy, and ground and highest excited eigenmodes and subsequently measuring their localization properties. Moreover, we also experimentally investigate nonequilibrium quench dynamics for photons and show that photonic Loschmidt echoes can identify the appearance of mobility edge phases. Our study thus opens new avenues for investigating energy-dependent photonic Anderson localizations and harnessing photons to explore intriguing nonequilibrium physics.
Phys. Rev. Lett. 134, 053601 (2025)
Integrated optics, Localization, Photonics
Emergent Metric-Like States of Active Particles with Metric-Free Polar Alignment
Research article | Biological self-organization | 2025-02-03 05:00 EST
Yinong Zhao, Cristián Huepe, and Pawel Romanczuk
We study a model of self-propelled particles interacting with their \(k\) nearest neighbors through polar alignment. By exploring its phase space as a function of two nondimensional parameters (alignment strength \(g\) and P'eclet number Pe), we identify two distinct order-disorder transitions. One occurs at a low critical \(g\) value independent of Pe, has no significant density-order coupling, and is consistent with the transition previously predicted by the mean-field approach. Up to the system sizes studied, it appears continuous. The other is discontinuous, depends on a combined control parameter involving Pe and \(g\) that controls the alignment strength, and results from the formation of small, dense, highly persistent clusters of particles that follow metric-like dynamics. These dense clusters form at a critical value of the combined control parameter \(\mathrm{Pe}/{g}^{\alpha }\), with \(\alpha \approx 1.5\), which appears to be valid for different alignment-based models. Our study shows that models of active particles with metric-free interactions can produce characteristic length scales and self-organize into metric-like collective states that undergo metric-like transitions.
Phys. Rev. Lett. 134, 058201 (2025)
Biological self-organization, Collective behavior, Emergence of patterns, Phase transitions, Collective dynamics, Living matter & active matter, Self-propelled particles, Theories of collective dynamics & active matter
Physical Review X
Theory of Robust Quantum Many-Body Scars in Long-Range Interacting Systems
Research article | Eigenstate thermalization | 2025-02-03 05:00 EST
Alessio Lerose, Tommaso Parolini, Rosario Fazio, Dmitry A. Abanin, and Silvia Pappalardi
A demonstration of quantum many-body scars arising from long-range interactions implies a surprising breakdown of conventional thermal equilibrium.
Phys. Rev. X 15, 011020 (2025)
Eigenstate thermalization, Excited-state quantum phase transitions, Quantum metrology, Quantum scars, Trapped ions
arXiv
Entropy of small subsystems in thermalizing systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-03 20:00 EST
We study the entropy of small subsystems in thermalizing quantum many-body systems governed by local Hamiltonians. Assuming the eigenstate thermalization hypothesis, we derive an analytical formula for the von Neumann entropy of equilibrated subsystems. This formula reveals how subsystem entropy depends on the microscopic parameters of the Hamiltonian and the macroscopic properties of the initial state. Furthermore, our results provide a theoretical explanation for recent numerical findings by Maceira and Läuchli, obtained via exact diagonalization.
Statistical Mechanics (cond-mat.stat-mech)
Active particles in moving traps: minimum work protocols and information efficiency of work extraction
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-03 20:00 EST
Janik Schüttler, Rosalba Garcia-Millan, Michael E. Cates, Sarah A. M. Loos
We revisit the fundamental problem of moving a particle in a harmonic trap in finite time with minimal work cost, and extend it to the case of an active particle. By comparing the Gaussian case of an Active Ornstein-Uhlenbeck particle and the non-Gaussian run-and-tumble particle, we establish general principles for thermodynamically optimal control of active matter beyond specific models. We show that the open-loop optimal protocols, which do not incorporate system-state information, are identical to those of passive particles but result in larger work fluctuations due to activity. In contrast, closed-loop (or feedback) control with a single (initial) measurement changes the optimal protocol and reduces the average work relative to the open-loop control for small enough measurement errors. Minimum work is achieved by particles with finite persistence time. As an application, we propose an active information engine which extracts work from self-propulsion. This periodic engine achieves higher information efficiency with run-and-tumble particles than with active Ornstein-Uhlenbeck particles. Complementing a companion paper that gives only the main results [arXiv:2407.18542], here we provide a full account of our theoretical calculations and simulation results. We include derivations of optimal protocols, work variance, impact of measurement uncertainty, and information-acquisition costs.
Statistical Mechanics (cond-mat.stat-mech)
Probability Distributions of the order parameter of the Ising Model at two loops
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-03 20:00 EST
There exists an entire family of universal PDFs of the magnetization mode of the three dimensional Ising model parameterized by \(\zeta = \lim_{L,\xi_{\infty}}L/\xi_{\infty}\) which is the ratio of the system size \(L\) to the bulk correlation length \(\xi_{\infty}\) with both the thermodynamic limit and the critical limit being taken simultaneously at fixed \(\zeta\). Recently, the probability distribution functions (PDFs) of the magnetization mode of the three-dimensional Ising model has been computed at one-loop in the \(\epsilon=4-d\) expansion [arXiv preprint arXiv:2407.12603 (2024)]. We show how these PDFs or, equivalently, the rate functions which are their logarithm, can be systematically computed at second order of the perturbative expansion. We compute the whole family of universal rate-functions and show that their agreement with the Monte Carlo data improves significantly at this order when compared to their one-loop counterpart.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
23 pages,4 figures
Report on Reproducibility in Condensed Matter Physics
New Submission | Other Condensed Matter (cond-mat.other) | 2025-02-03 20:00 EST
A. Akrap, D. Bordelon, S. Chatterjee, E. D. Dahlberg, R. P. Devaty, S. M. Frolov, C. Gould, L. H. Greene, S. Guchhait, J. J. Hamlin, B. M. Hunt, M. J. A. Jardine, M. Kayyalha, R. C. Kurchin, V. Kozii, H. F. Legg, I. I. Mazin, V. Mourik, A. B. Özgüler, J. Peñuela-Parra, B. Seradjeh, B. Skinner K. F. Quader, J. P. Zwolak
We present recommendations for how to improve reproducibility in the field of condensed matter physics. This area of physics has consistently produced both fundamental insights into the functioning of matter as well as transformative inventions. Our recommendations result from a collaboration that includes researchers in academia and government laboratories, scientific journalists, legal professionals, representatives of publishers, professional societies, and other experts. The group met in person in May 2024 at a conference at the University of Pittsburgh to discuss the growing challenges related to research reproducibility in condensed matter physics. We discuss best practices and policies at all stages of the scientific process to safeguard the value condensed matter research brings to society. We look forward to comments and suggestions, especially regarding subfield-specific recommendations, and will incorporate them into the next version of the report.
Other Condensed Matter (cond-mat.other), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con), Physics and Society (physics.soc-ph)
From non-equilibrium Green functions to Lattice Wigner: A toy model for quantum nanofluidics simulations
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-03 20:00 EST
S. Succi, M. Lauricella, A. Tiribocchi
Recent experiments of fluid transport in nano-channels have shown evidence of a dramatic reduction of friction due to the coupling between charge-fluctuations in polar fluids and electronic excitations in graphene solids, a phenomenon dubbed "negative quantum friction". In this paper, we present a semi-classical mesoscale Boltzmann-Wigner lattice kinetic model of quantum-nanoscale transport and perform a numerical study of the effects of the quantum interactions on the evolution of a one-dimensional nano-fluid subject to a periodic external potential. It is shown that the effects of quantum fluctuations become visible once the quantum length scale (Fermi wavelength) of the quasiparticles becomes comparable to the wavelength of the external potential. Under such conditions, quantum fluctuations are mostly felt on the odd kinetic moments, while the even ones remain nearly unaffected because they are "protected" by thermal fluctuations. It is hoped that the present Boltzmann-Wigner lattice model and extensions thereof may offer a useful tool for the computer simulation of quantum-nanofluidic transport phenomena.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computational Physics (physics.comp-ph), Fluid Dynamics (physics.flu-dyn)
9 pages, 6 figures
Classical Information Exchange Between Particles
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-03 20:00 EST
Miles Miller-Dickson, Christopher Rose
The flow of information within many-body systems is a fundamental feature of physical interaction. Given an underlying classical physics model for the interaction between a particle and its environment, we give meaning to and quantify the information passed between them over time. We show that the maximum information exchange rate is proportional to the ratio of inter-particle energy flow and initial particle energy -- a sort of signal-to-noise ratio. In addition, a single time-point (as opposed to trajectory) observability relation emerges.
Statistical Mechanics (cond-mat.stat-mech)
Exploring the accuracy of the equation-of-motion coupled-cluster band gap of solids
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
Evgeny Moerman, Henrique Miranda, Alejandro Gallo, Andreas Irmler, Tobias Schäfer, Felix Hummel, Manuel Engel, Georg Kresse, Matthias Scheffler, Andreas Grüneis
While the periodic equation-of-motion coupled-cluster (EOM-CC) method promises systematic improvement of electronic band gap calculations in solids, its practical application at the singles and doubles level (EOM-CCSD) is hindered by severe finite-size errors in feasible simulation cells. We present a hybrid approach combining EOM-CCSD with the computationally efficient \(GW\) approximation to estimate thermodynamic limit band gaps for several insulators and semiconductors. Our method substantially reduces required cell sizes while maintaining accuracy. Comparisons with experimental gaps and self-consistent \(GW\) calculations reveal that deviations in EOM-CCSD predictions correlate with reduced single excitation character of the excited many-electron states. Our work not only provides a computationally tractable approach to EOM-CC calculations in solids but also reveals fundamental insights into the role of single excitations in electronic-structure theory.
Materials Science (cond-mat.mtrl-sci)
7 (+12 supplementary) pages, 3(+7) figures
Quantum Phase Transitions between Symmetry-Enriched Fracton Phases
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-03 20:00 EST
Julian Boesl, Yu-Jie Liu, Wen-Tao Xu, Frank Pollmann, Michael Knap
Phases with topological order exhibit further complexity in the presence of global symmetries: States with the same topological order are distinguished by how their anyonic excitations transform under these symmetries, leading to a classification in terms of symmetry-enriched topological phases. In this work, we develop a generic scheme to study an analogous situation for three-dimensional fracton phases by means of isometric tensor network states (isoTNS) with finite bond dimension, which allow us to tune between wavefunctions of different symmetry fractionalization. We focus on the X-Cube model, a paradigmatic fracton model hosting two types of excitations: lineons, which are mobile in a single direction only, and fractons that are completely immobile as individual particles. By deforming the local tensors that describe the ground state of the fixed point model, we find a family of exact wavefunctions for which the symmetry fractionalization under an anti-unitary symmetry on both types of excitations is directly visible. These wavefunctions have non-vanishing correlation lengths and are non-stabilizer states. At the critical points between the phases, power-law correlations are supported in certain spatial directions. Furthermore, based on the isoTNS description of the wavefunction, we determine a linear-depth quantum circuit to sequentially realize these states on a quantum processor, including a holographic scheme for which a pair of two-dimensional qubit arrays suffices to encode the three-dimensional state using measurements. Our approach provides a construction to enrich phases with exotic topological or fracton order based on the language of tensor networks and offers a tractable route to implement and characterize fracton order with quantum processors.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
22 pages, 10 figures
Unconventional high-temperature excitonic insulators in two-dimensional topological materials
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-03 20:00 EST
L. Maisel Licerán, H. T. C. Stoof
Bound electron-hole pairs in semiconductors known as excitons can form a coherent state at low temperatures akin to a BCS condensate. The resulting phase is known as the excitonic insulator and has superfluid properties. Here we theoretically study the excitonic insulator in a pair of recently proposed two-dimensional candidate materials with nontrivial band topology. Contrary to previous works, we include interaction channels that violate the individual electron and hole number conservations. These are on equal footing with the number-conserving processes due to the substantial overlap of Wannier orbitals of different bands, which cannot be exponentially localized due to the nontrivial Chern numbers of the latter. Their inclusion is crucial to determine the symmetry of the electron-hole pairing, and by performing mean-field calculations at nonzero temperatures we find that the order parameter is a chiral \(d\)-wave. We discuss the nontrivial topology of this unconventional state and analyze its superfluid properties. In particular, we estimate BKT temperatures between 75 K and 100 K on realistic substrates, over an order of magnitude larger than in the number-conserving approximation where \(s\)-wave pairing is favored. Our results highlight the interplay between topology at the single-particle level and long-range interactions, motivating further research in systems where both phenomena coexist.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
Pressure induced enhancement of polar distortions in a metal, and implications on the Rashba spin-splitting
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-03 20:00 EST
Evie Ladbrook, Urmimala Dey, Nicholas C. Bristowe, Robin S. Perry, Dominik Daisenberger, Mark R. Warren, Mark S. Senn
Polar metals are an intriguing class of materials in which electric polarisation and metallicity can coexist within a single phase. The unique properties of polar metals challenge expectations, making way for the exploration of exotic phenomena such as unconventional magnetism, hyperferroelectric multiferroicity and developing multifunctional devices that can leverage both the materials electric polarization and its asymmetry in the spin conductivity, that arises due to the Rashba effect. Here, via a high pressure single crystal diffraction study, we report the pressure-induced enhancement of polar distortions in such a metal, Ca\(_3\)Ru\(_2\)O\(_7\). Our DFT calculations highlight that naive assumptions about the linear dependency between polar distortion amplitudes and the magnitude of the Rashba spin splitting may not be generally valid.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Mitigation of Delamination of Epitaxial Large-Area Boron Nitride for Semiconductor Processing
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
Jakub Rogoza, Jakub Iwanski, Katarzyna Ludwiczak, Bartosz Furtak, Aleksandra Krystyna Dabrowska, Mateusz Tokarczyk, Johannes Binder, Andrzej Wysmolek
Hexagonal boron nitride (hBN) is a promising material for next-generation semiconductor and optoelectronic devices due to its wide bandgap and remarkable optical properties. To apply this material in the semiconductor industry, it is necessary to grow large-area layers on the wafer-scale. For this purpose, chemical vapor deposition methods are highly preferable. However, in the case of epitaxial BN, its fragility and susceptibility to delamination and fold formation during wet processing, such as lithography, present significant challenges to its integration into device fabrication. In this work, we introduce a controlled delamination and redeposition method that effectively prevents the layer from degradation, allowing for multi-step lithographic processes. This approach is applicable to BN layers across a broad thickness range, from tens to hundreds of nanometers, and ensures compatibility with standard photolithographic techniques without compromising the material's intrinsic properties. By addressing key processing challenges, this method paves the way for integrating epitaxial BN into advanced semiconductor and optoelectronic technologies.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
12 pages, 4 figures
Subharmonic spin correlations and spectral pairing in Floquet time crystals
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-03 20:00 EST
Alexander-Georg Penner, Harald Schmid, Leonid I. Glazman, Felix von Oppen
Floquet time crystals are characterized by subharmonic behavior of temporal correlation functions. Studying the paradigmatic time crystal based on the disordered Floquet quantum Ising model, we show that its temporal spin correlations are directly related to spectral characteristics and that this relation provides analytical expressions for the correlation function of finite chains, which compare favorably with numerical simulations. Specifically, we show that the disorder-averaged temporal spin correlations are proportional to the Fourier transform of the splitting distribution of the pairs of eigenvalues of the Floquet operator, which differ by \(\pi\) to exponential accuracy in the chain length. We find that the splittings are well described by a log-normal distribution, implying that the temporal spin correlations are characterized by two parameters. We discuss possible implications for the phase diagram of the Floquet time crystals.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Physics (quant-ph)
9 pages, 4 figures
Physics-informed Neural Model Predictive Control of Interacting Active Brownian Particles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-03 20:00 EST
Titus Quah, Sho C. Takatori, James B. Rawlings
Active matter systems, composed of self-propelled agents that convert energy into directed motion, exhibit a wide range of emergent behaviors, such as motility-induced phase separation, flocking, and swarming. These phenomena, observed across natural and engineered systems, hold immense potential for applications in programmable materials, directed assembly, and micro-robotics. However, precisely controlling their macroscopic continuum fields, e.g., density or flux, remains a significant challenge due to the complexity of multibody interactions and correlated particle dynamics. To address this challenge, we present a framework that combines physics-informed machine learning with Model Predictive Control. Our approach learns a closure model for complex particle interactions while incorporating known physical principles, resulting in an accurate predictive model suitable for real-time control. By integrating this model into a Model Predictive Control framework, we enable systematic optimization of control actions that can guide the system toward desired macroscopic behaviors. Through two illustrative examples, we showcase the versatility of the framework. First, we control the spatial distribution of particles by splitting them into two groups and dynamically juggling their densities. Second, we simultaneously control both the number density and the mean flux, guiding the latter to follow a prescribed sinusoidal profile. These results highlight the framework's potential to systematically control complex dynamics in active matter systems and provide a foundation for broader applications in programmable and adaptive materials.
Soft Condensed Matter (cond-mat.soft)
BARCODE: Biomaterial Activity Readouts to Categorize, Optimize, Design and Engineer for high throughput screening and characterization of dynamically restructuring soft materials
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-03 20:00 EST
Qiaopeng Chen, Aditya Sriram, Ayan Das, Katarina Matic, Maya Hendija, Keegan Tonry, Jennifer L. Ross, Moumita Das, Ryan J. McGorty, Rae M. Robertson-Anderson, Megan T. Valentine
Active, responsive, nonequilibrium materials, at the forefront of materials engineering, offer dynamical restructuring, mobility and other complex life-like properties. Yet, this enhanced functionality comes with significant amplification of the size and complexity of the datasets needed to characterize their properties, thereby challenging conventional approaches to analysis. To meet this need, we present BARCODE (Biomaterial Activity Readouts to Categorize, Optimize, Design and Engineer), an open-access software that automates high throughput screening of microscopy video data to enable nonequilibrium material optimization and discovery. BARCODE produces a unique fingerprint or barcode of performance metrics that visually and quantitatively encodes dynamic material properties with minimal file size. Using three complementary material agnostic analysis branches, BARCODE significantly reduces data dimensionality and size, while providing rich, multiparametric outputs and rapid tractable characterization of activity and structure. We analyze a series of datasets of cytoskeleton networks and cell monolayers to demonstrate the ability of BARCODE to accelerate and streamline screening and analysis, reveal unexpected correlations and emergence, and enable broad non-expert data access, comparison, and sharing.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Topological Transitions, Pinning and Ratchets for Driven Magnetic Hopfions in Nanostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-03 20:00 EST
J. C. Bellizotti Souza, C. J. O. Reichhardt, C. Reichhardt, A. Saxena, N. P. Vizarim, P. A. Venegas
Using atomistic simulations, we examine the dynamics of three-dimensional magnetic hopfions interacting with an array of line defects or posts as a function of defect spacing, defect strength, and current. We find a pinned phase, a sliding phase where a hopfion can move through the posts or hurdles by distorting, and a regime where the hopfion becomes compressed and transforms into a toron that is half the size of the hopfion and moves at a lower velocity. The toron states occur when the defects are strong; however, in the toron regime, it is possible to stabilize sliding hopfions by increasing the applied current. Hopfions move without a Hall angle, while the toron moves with a finite Hall angle. We also show that when a hopfion interacts with an asymmetric array of planar defects, a ratchet effect consisting of a net dc motion can be realized under purely ac driving.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 7 figures
Universal Efimov Scaling in the Rabi-Coupled Few-Body Spectrum
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-03 20:00 EST
Anthony N. Zulli, Brendan C. Mulkerin, Meera M. Parish, Jesper Levinsen
We investigate the behavior of the Efimov effect -- a universal quantum few-body phenomenon -- in the presence of an external driving field. Specifically, we consider up to three bosonic atoms, such as \(^{133}\)Cs, interacting with a light atom, such as \(^{6}\)Li, where the latter has two internal spin states \(\{\uparrow, \downarrow\}\) that are Rabi coupled. Assuming that only the spin-\(\uparrow\) light atom interacts with the bosons, we find that the Rabi drive transposes the entire Efimov spectrum such that the Efimov trimers and tetramers are centered around the Rabi-shifted two-body scattering resonance. Crucially, we show that the Rabi drive preserves the trimers' discrete scaling symmetry, while universally shifting the Efimov three-body parameter, leading to a log-periodic modulation in the spectrum as the Rabi drive is varied. Our results suggest that Efimov physics can be conveniently explored using an applied driving field, opening up the prospect of an externally tunable three-body parameter.
Quantum Gases (cond-mat.quant-gas)
13 pages, 8 figures + supplemental material
Programmable Synthetic Magnetism and Chiral Edge States in Nano-Optomechanical Quantum Hall Networks
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-03 20:00 EST
Jesse J. Slim, Javier del Pino, Ewold Verhagen
Artificial magnetic fields break time-reversal symmetry in engineered materials--also known as metamaterials, enabling robust, topological transport of neutral excitations, much like electronic conduction edge channels in the integer quantum Hall effect. We experimentally demonstrate the emergence of quantum-Hall-like chiral edge states in optomechanical resonator networks. Synthetic magnetic fields for phononic excitations are induced through laser drives, while cavity optomechanical control allows full reconfigurability of the effective metamaterial response of the networks, including programming of magnetic fluxes in multiple resonator plaquettes. By tuning the interplay between network connectivity and magnetic fields, we demonstrate both flux-sensitive and flux-insensitive localized mechanical states. Scaling up the system creates spectral features that are precursors to Hofstadter butterfly spectra. Site-resolved spectroscopy reveals edge-bulk separation, with stationary phononic distributions signaling chiral edge modes. We directly probe those edge modes in transport measurements to demonstrate a unidirectional acoustic channel. This work unlocks new ways of controlling topological phononic phases at the nanoscale with applications in noise management and information processing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics), Quantum Physics (quant-ph)
Main text (6 pages, 4 figures), Appendices (7 pages, 3 figures)
Direct Visualization of an Incommensurate Unidirectional Charge Density Wave in La\(_4\)Ni\(_3\)O\(_{10}\)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-02-03 20:00 EST
Mingzhe Li, Jiashuo Gong, Yinghao Zhu, Ziyuan Chen, Jiakang Zhang, Enkang Zhang, Yuanji Li, Ruotong Yin, Shiyuan Wang, Jun Zhao, Dong-Lai Feng, Zengyi Du, Ya-Jun Yan
Superconductivity emerges in both La\(_3\)Ni\(_2\)O\(_7\) and La\(_4\)Ni\(_3\)O\(_{10}\) under high pressure by suppressing their density-wave transitions, but critical temperature (Tc) differs significantly between these two compounds. To gain deeper insights into the distinct superconducting states, it is essential to unravel the nature of the density-wave states at ambient pressure, a topic that remains largely unexplored. Here, using scanning tunneling microscopy/spectroscopy (STM/STS), we report the direct visualization of an incommensurate unidirectional charge density wave (CDW) in La\(_4\)Ni\(_3\)O\(_{10}\) in real space. The density of states (DOS) is strongly depleted near \(E_F\), indicating the opening of a CDW gap of \(2{\Delta} \approx 71\) meV, which is unfavorable for the formation of superconductivity at ambient pressure. We propose that the CDW arises from Fermi surface nesting, and is likely a subsidiary phase of a spin density wave. Compared to La\(_3\)Ni\(_2\)O\(_7\), the weaker electronic correlation in La\(_4\)Ni\(_3\)O\(_{10}\) is likely one reason for the lower \(T_c\).
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 4 figures
Effects of GaAs Buffer Layer on Structural, Magnetic, and Transport Properties of Magnetic Topological Insulators Cr\(_y\)(Bi\(_x\)Sb\(_{1-x}\))\(_{2-y}\)Te\(_3\) and V\(_y\)(Bi\(_x\)Sb\(_{1-x}\))\(_{2-y}\)Te\(_3\) Films
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-03 20:00 EST
Yusuke Nakazawa, Takafumi Akiho, Kiyoshi Kanisawa, Hiroshi Irie, Norio Kumada, Koji Muraki
Here, we study the effects of a GaAs buffer layer on the structural, magnetic, and transport properties of Cr\(_y\)(Bi\(_x\)Sb\(_{1-x}\))\(_{2-y}\)Te\(_3\) magnetic topological insulator thin films and compare them with those of V\(_y\)(Bi\(_x\)Sb\(_{1-x}\))\(_{2-y}\)Te\(_3\), which we recently reported. Similar to the case of V\(_y\)(Bi\(_x\)Sb\(_{1-x}\))\(_{2-y}\)Te\(_3\), growth on a GaAs buffer layer leads to some distinctly different properties than direct growth on InP substrates. These include improved interface quality confirmed by transmission electron microscopy, enhanced magnetic coercive fields, and smaller resistivity peaks at the magnetization reversals. Furthermore, the Bi-ratio dependence of the carrier density reveals that the interface property also affects the Fermi level. These results demonstrate the importance of the buffer layer in controlling the electronic properties of the magnetic topological insulator films.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
10 pages, 3 figures. The following article has been accepted by physica status solidi (b). After it is published, it will be found at this https URL
Electrical conductivity of conductive films based on random metallic nanowire networks
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-03 20:00 EST
Yuri Yu. Tarasevich, Andrei V. Eserkepov, Irina V. Vodolazskaya
Using computer simulation, we investigated the dependence of the electrical conductivity of random two-dimensional systems of straight nanowires on the main parameters. Both the resistance of the conductors and the resistance of the contacts between them were taken into account. The dependence of the resistance, \(R\), between network nodes on the distance between nodes, \(r\), is \(R(r) = R_\Box/\pi \ln r + \mathrm{const}\), where \(R_\Box\) is the sheet resistance.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
5 pages, 4 figures, 1 table, 26 refs
Synthesis of spherical mesoporous silica beads with tunable size, stiffness and porosity
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-03 20:00 EST
M. Milani, K. Ahmad, E. Cavalletti, C. Ligoure, L. Cipelletti, M. Kongkaew, P. Trens, L. Ramos
We present an innovative template-free water-based sol-gel method to produce uniform mesoporous silica beads of millimeter size, which have tunable size, stiffness and porosity, and could be used for adsorption applications. Our protocol exploits an in-situ enzymatic reaction to produce spherical beads of hydrogel from a charge-stabilized suspension of silica nanoparticles confined in a millimetric drop suspended in a non-miscible oil. Once the gelation step is complete, the spherical bead of gel is cleaned from oil and deposited onto a hydrophobic surface and let dry. Separating the gelation to the drying steps ensures a spatially uniform gel and allows us to perform a solvent exchange before drying. For all beads, we observe a crack-free drying process leading to the formation of stiff quasi-spherical beads with diameter in the range 1 to 5 mm and Young modulus in the range \((0.1-2)\) GPa and narrow pore size distribution, centered around \(10\) to \(25\) nm depending on the experimental conditions. Finally, to demonstrate the potentiality of these materials, we graft on the bead surface aminosilane molecules, and quantify their CO\(_2\) adsorption efficiency. Overall, the production method we have developed is simple, readily adaptable, and offers promising materials for adsorption, storage, catalysis and chromatography.
Soft Condensed Matter (cond-mat.soft)
Magnetizing weak links by time-dependent spin-orbit interactions: momentum conserving and non-conserving processes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-03 20:00 EST
Debashree Chowdhury, O. Entin-Wohlman, A. Aharony, R. I. Shekhter, M. Jonson
Rashba spin-orbit interactions generated by time-dependent electric fields acting on weak links (that couple together non-magnetic macroscopic leads) can magnetize the junction. The Rashba spin-orbit interaction that affects the spins of electrons tunneling through the weak links changes their momentum concomitantly. We establish the connection between the magnetization flux induced by processes that conserve the momentum and the magnetization created by tunneling events that do not. Control of the induced magnetization can be achieved by tuning the polarization of the AC electric field responsible for the spin-orbit Rashba interaction (e.g., from being circular to linear), by changing the applied bias voltage, and by varying the degree of a gate voltage-induced asymmetry of the device.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
11 pages, 3 figures
Electrically Tunable Picosecond-scale Octupole Fluctuations in Chiral Antiferromagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-03 20:00 EST
Shiva T. Konakanchi, Sagnik Banerjee, Mohammad M. Rahman, Yuta Yamane, Shun Kanai, Shunsuke Fukami, Pramey Upadhyaya
We present a theory for the relaxation time of the octupole order parameter in nanoscale chiral antiferromagnets (AFMs) coupled to thermal baths and spin injection sources. Using stochastic spin dynamics simulations, we demonstrate that the octupole moment relaxes through two distinct mechanisms\(-\)escape over a barrier and precessional dephasing\(-\)as the barrier for octupole fluctuations is lowered relative to the thermal energy. Notably, the octupole moment relaxes orders of magnitude faster than the typical dipolar order parameters, reaching picosecond timescales. By combining Langer's theory with an effective low-energy description of octupole dynamics in chiral AFMs, we derive analytical expressions for the relaxation times. We find that relaxation in chiral AFMs parallels dipole relaxation in XY magnets, with exchange fields serving the role of the dipole fields. Further, by drawing on the analogy between order parameter dynamics in XY magnets under spin injection and current-biased Josephson junctions, we propose a new scheme for electrically tuning the octupole relaxation times. Our work offers fundamental insights for the development of next-generation spintronic devices that harness octupole order parameters for information encoding, especially in octupole-based probabilistic computing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech), Applied Physics (physics.app-ph)
Emergence of Topological Non-Fermi Liquid Phases in a Modified Su-Schrieffer-Heeger Chain with Long-Range Interactions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-03 20:00 EST
Sepide Mohamadi, Jahanfar Abouie
In this study, we investigate the emergence of a topological non-Fermi liquid (NFL) phase in a modified Su-Schrieffer-Heeger (SSH) chain model subjected to long-range interactions characterized by the Hatsugai-Kohmoto (HK) model. While Fermi liquid theory has been instrumental in understanding low temperature properties of metals, it fails to account for the complex behaviors exhibited by strongly correlated systems, where interactions lead to emergent phenomena such as non-Fermi liquid behavior. Our analysis reveals that the SSH-HK model supports a rich ground state phase diagram, exhibiting distinct NFL phases marked by many body Zak phases of \(2\pi\) and \(0\), corresponding to topological and trivial NFL states, respectively. We demonstrate that the topological NFL state manifests unique electronic polarization characteristics akin to those in the non-interacting SSH model. Through exact diagonalization of the interacting SSH-HK Hamiltonian, we explore the spectral functions and density of states, revealing significant departures from traditional quasiparticle behavior in various particle number sectors. Our findings extend the understanding of topological non-Fermi liquids and their potential implications for high-temperature superconductivity and other correlated electron systems, highlighting the intricate interplay between topology and strong electron correlations.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
13 pages, 27 figures
Impact of Nanoscopic Impurity Aggregates on Cavitation in Water
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-03 20:00 EST
Marin Šako, Roland R. Netz, Matej Kanduč
The stability of water against cavitation under negative pressures is a phenomenon known for considerable discrepancies between theoretical predictions and experimental observations. Using a combination of molecular dynamics simulations and classical nucleation theory, we explore how nanoscopic hydrocarbon droplets influence cavitation in water. Our findings reveal that while a macroscopic volume of absolutely pure water withstands up to -120 MPa of tension, introducing a single nanoscopic oil droplet, merely a few nanometers in radius, brings this cavitation threshold to around -30 MPa, closely matching the values typically observed in highly controlled experiments. The unavoidable presence of nanoscopic hydrophobic impurities, even in highly purified water used in experiments, imposes a practical limit on achieving the theoretical tensile strength in realistic settings. More broadly, our study highlights the profound impact of nonpolar residues on nucleation phenomena and enhances our understanding of metastability in real-world systems.
Soft Condensed Matter (cond-mat.soft)
8 pages, 5 figures
Quantum effects in surface diffusion: application to diffusion of nitrogen adatoms over GaN(0001) surface
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
Paweł Strak, Cyprian Sobczak, Stanislaw Krukowski
It is shown that quantum effects play determining role in nitrogen adatom diffusion due to several different factors. This could be related to the change of the energy of the quantum states and also due to the redistribution of electrons between the quantum states, both full and resonant, via quantum statistics partially governed by the Fermi energy level. These effects were studied in the case of nitrogen diffusion over clean and gallium covered Ga-terminated GaN(0001) surface. For the fractional coverage the density functional theory (DFT) calculations show that at the saddle point configuration the redistribution of electrons between different quantum states may affect the surface diffusion barrier significantly. The other quantum influence occurs via the change of the minimal energy configuration. Under fractional Ga coverage of GaN(0001) surface the nitrogen diffusion energy barrier proceeds from the resonant states governed energy minimal H3 site across the saddle point in the bridge configuration. At this path the barrier is affected the electron redistribution between surface quantum states both in the initial and the saddle point. In the case of the full GaN coverage the diffusion path is from on-top N adatom configuration via H3 site that corresponds to maximal energy. Therefore the diffusion barrier is Ebar= 1.18 eV for clean and Ebar= 0.92 eV for (1/6) ML to finally Ebar= 1.23 eV for full Ga coverage. Thus the overall barrier is reduced to Ebar= 0.92 eV due to quantum statistics effects. The identified stable N on-top configuration for the full coverage is essential for atomic mechanism of GaN growth in Ga-rich regime.
Materials Science (cond-mat.mtrl-sci)
41 pages, 14 figures
Novel Magnetic Materials for Spintronic Device Technology
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
Spintronics, a transformative field of research, leverages the spin of electron to revolutionize electronic devices, offering significant advantages over traditional charge-based systems. This chapter highlights the critical role of novel magnetic materials in advancing spintronic technologies by addressing their fundamental properties, fabrication methods, and applications. A diverse range of materials, including ferromagnetic, antiferromagnetic, non-collinear antiferromagnetic, synthetic antiferromagnetic, ferrimagnetic, and multiferroic systems, is explored for their unique contributions to spintronic devices. Advanced fabrication techniques, such as bulk crystal formation, thin-film deposition, and nano-structuring, are detailed along characterization methods including spin-orbit torque analysis and magnetization dynamics studies. Emerging research on three-dimensional spin textures, domain walls, skyrmions, and magnons highlighted for its potential for novel spintronic applications. Additionally, the chapter reviews applications in memory technologies, spintronic nano-oscillators, and neuromorphic computing. Finally, it concludes by examining future research directions, challenges, and opportunities in spintronics, providing insights into breakthroughs that are shaping the future of this rapidly evolving field.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
75 pages, 13 figures
Learning the Hamiltonian Matrix of Large Atomic Systems
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
Chen Hao Xia, Manasa Kaniselvan, Alexandros Nikolaos Ziogas, Marko Mladenović, Rayen Mahjoub, Alexander Maeder, Mathieu Luisier
Graph neural networks (GNNs) have shown promise in learning the ground-state electronic properties of materials, subverting ab initio density functional theory (DFT) calculations when the underlying lattices can be represented as small and/or repeatable unit cells (i.e., molecules and periodic crystals). Realistic systems are, however, non-ideal and generally characterized by higher structural complexity. As such, they require large (10+ Angstroms) unit cells and thousands of atoms to be accurately described. At these scales, DFT becomes computationally prohibitive, making GNNs especially attractive. In this work, we present a strictly local equivariant GNN capable of learning the electronic Hamiltonian (H) of realistically extended materials. It incorporates an augmented partitioning approach that enables training on arbitrarily large structures while preserving local atomic environments beyond boundaries. We demonstrate its capabilities by predicting the electronic Hamiltonian of various systems with up to 3,000 nodes (atoms), 500,000+ edges, ~28 million orbital interactions (nonzero entries of H), and $$0.55% error in the eigenvalue spectra. Our work expands the applicability of current electronic property prediction methods to some of the most challenging cases encountered in computational materials science, namely systems with disorder, interfaces, and defects.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn)
*Equal Contribution
Towards numerically exact computation of conductivity in the thermodynamic limit of interacting lattice models
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-03 20:00 EST
Jeremija Kovačević, Michel Ferrero, Jakša Vučičević
Computing dynamical response functions in interacting lattice models is a long standing challenge in condensed matter physics. In view of recent results, the dc resistivity \(\rho_\mathrm{dc}\) in the weak coupling regime of the Hubbard model is of great interest, yet it is not fully understood. The challenge lies in having to work with large lattices while avoiding analytical continuation. The weak-coupling \(\rho_\mathrm{dc}\) results were so far computed at the level of the Boltzmann theory and at the level of the Kubo bubble approximation, which neglects vertex corrections. Neither theory was so far rigorously proven to give exact results even at infinitesimal coupling, and the respective dc resistivity results differ greatly. In this work we develop, cross-check and apply two state-of-the-art methods for obtaining dynamical response functions. We compute the optical conductivity at weak coupling in the Hubbard model in a fully controlled way, in the thermodynamic limit and without analytical continuation. We show that vertex corrections persist to infinitesimal coupling, with a constant ratio to the Kubo bubble. We connect our methods with the Boltzmann theory, and show that the latter applies additional approximations, which lead to quantitatively incorrect scaling of \(\rho_\mathrm{dc}\) with respect to the coupling constant.
Strongly Correlated Electrons (cond-mat.str-el)
5 pages, 3 figures + supplemental material, 13 pages, 16 figures
Optimal constrained control for generally damped Brownian heat engines
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-03 20:00 EST
Monojit Chatterjee, Viktor Holubec, Rahul Marathe
We investigate maximum power and efficiency protocols for cyclic heat engines based on a generally damped Brownian particle confined in a harmonic potential, subject to experimentally motivated constraints on the potential stiffness and bath temperature. These constraints render traditional geometric and mass transport methods inapplicable, as they rely on fixed control or response parameters at specific points in the cycle. Instead, we develop an iterative algorithm grounded in optimal control theory, enabling simultaneous optimization of cycle time and the time-dependent variations of stiffness and temperature. We validate the algorithm against analytical results in the deeply overdamped regime and extend its application to systems with general damping rates. As the damping rate decreases from a deeply overdamped to a deeply underdamped regime, the maximum power diminishes to zero, and the corresponding cycle time diverges. For a fixed cycle time, the maximum efficiency exhibits a comparable trend. In the generally damped regime, the stiffness and temperature protocols display intricate, non-monotonic features, in stark contrast to the simpler patterns observed in extreme damping limits. Furthermore, optimizing the temperature profile significantly enhances efficiency, particularly in intermediate damping regimes. Our findings demonstrate how experimental constraints fundamentally influence optimal control protocols.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
18 pages, 7 figures, 1 table
Fractons from covariant higher-rank 3D BF theory
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-03 20:00 EST
Erica Bertolini, Alberto Blasi, Matteo Carrega, Nicola Maggiore, Daniel Sacco Shaikh
In this paper we study the 3D gauge theory of two tensor gauge fields: \(a_{\mu\nu}(x)\), which we take symmetric, and \(B_{\mu\nu}(x)\), with no symmetry on its indices. The corresponding invariant action is a higher-rank BF-like model, which is first considered from a purely field theoretical point of view, and the propagators with their poles and the degrees of freedom are studied. Once matter is introduced, a fracton behaviour naturally emerges. We show that our theory can be mapped to the low-energy effective field theory describing the Rank-2 Toric Code (R2TC). This relation between our covariant BF-like theory and the R2TC is a higher-rank generalization of the equivalence between the ordinary 3D BF theory and the Kitaev's Toric Code. In the last part of the paper we analyze the case in which the field \(B_{\mu\nu}(x)\) is a symmetric tensor. It turns out that the obtained BF-like action can be cast into the sum of two rank-2 Chern-Simons actions, thus generalizing the ordinary abelian case. Therefore, this represents a higher-rank generalization of the ordinary 3D BF theory, which well describes the low-energy physics of quantum spin Hall insulators in two spatial dimensions.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), High Energy Physics - Theory (hep-th)
36 pages, no figures
In-operando test of tunable Heusler alloys for thermomagnetic harvesting of low-grade waste heat
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
F. Cugini, L. Gallo, G. Garulli, D. Olivieri, G. Trevisi, S. Fabbrici, F. Albertini, M. Solzi
Thermomagnetic generation stands out as a promising technology for harvesting and converting low-grade waste heat below 100 °C. Despite the exponential growth in research on thermomagnetic materials and prototypes over the last decade, there remains, to unlock the full potential of this technology, a critical gap between fundamental research on materials and the design of advanced devices. In this study, we present the in-operando assessment of thermomagnetic performance of three representative Ni,Mn-based Heusler alloys optimized for harvesting low-grade waste heat below 373 K. These materials were tested under operational conditions using a specially designed laboratory-scale prototype of a thermomagnetic motor. The mechanical power output of the motor, operated with NiMnIn, NiMnSn and NiMnCuGa alloys, was correlated with the magnetic properties of the materials, highlighting the critical role of the magnetic transition temperature and saturation magnetization in determining the efficiency of thermomagnetic energy conversion. Austenitic Heusler alloys were confirmed to be promising thermomagnetic materials due to their highly tunable Curie temperature and significant magnetization changes in the 300-360 K temperature range. Among the tested materials, the Ni48Mn36In16 alloy demonstrated the highest thermomagnetic performance, surpassing the benchmark material Gd in the 320-340 K range. From an experimental perspective, the developed prototype of thermomagnetic motor serves as a flexible test-bench for evaluating and comparing the thermomagnetic performance of small amounts (less than 0.3 g) of new materials under variable conditions. Additionally, its modular design facilitates testing and optimization of its various components, thereby contributing to the advancement of thermomagnetic motor technology.
Materials Science (cond-mat.mtrl-sci)
Signatures of Non-Abelian Kitaev quantum spin liquids in noise magnetormetry
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-03 20:00 EST
Xiao Xiao, Masahiro O. Takahashi, Paul Stevenson, Satoshi Fujimoto, Arun Bansil
Identification of isolated Majorana zero modes (MZMs) is a key step towards the realization of fault-tolerant topological quantum computation. Here we show how the \(T_1\)-based noise magnetormetry of a nitrogen-vacancy (NV) center qubit can reveal the unique signatures of Majorana fermions attached to vacancies in a non-Abelian Kitaev quantum spin liquid (KQSL). The \(1/T_1\) of the NV center is found to be increased significantly when the working frequency of the NV center matches the energy difference between a MZM and a low-energy hybridized mode involving dangling Majorana fermions adjacent to vacancies. In experiments, this energy difference can be tuned by an external Zeeman field. Because of the large excitation gap of flipping a local \(Z_2\) gauge field, the \(1/T_1\) spectrum is robust against other fluctuations in KQSLs. Our study presents a promising pathway for identifying the non-Abelian phase in Kitaev materials.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Spin Hall magnetoresistance at the altermagnetic insulator/Pt interface
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-03 20:00 EST
Miina Leiviskä, Reza Firouzmandi, Kyo-Hoon Ahn, Peter Kubaščik, Zbynek Soban, Satya Prakash Bommanaboyena, Christoph Müller, Dominik Kriegner, Sebastian Sailler, Michaela Lammel, Kranthi Kumar Bestha, Libor Šmejkal, Jakub Zelezny, Anja U. B. Wolter, Monika Scheufele, Johanna Fischer, Matthias Opel, Stephan Geprägs, Matthias Althammer, Bernd Büchner, Tomas Jungwirth, Lukáš Nádvorník, Sebastian T. B. Goennenwein, Vilmos Kocsis, Helena Reichlová
The resistance of a heavy metal can be modulated by an adjacent magnetic material through the combined effects of the spin Hall effect, inverse spin Hall effect, and dissipation of the spin accumulation at the interface. This phenomenon is known as spin Hall magnetoresistance. The dissipation of the spin accumulation can occur via various mechanisms, with spin-transfer torque being the most extensively studied. In this work, we report the observation of spin Hall magnetoresistance at the interface between platinum and an insulating altermagnetic candidate, Ba\(_2\)CoGe\(_2\)O\(_7\). Our findings reveal that this heterostructure exhibits a relatively large spin Hall magnetoresistance signal, which is anisotropic with respect to the crystal orientation of the current channel. We explore and rule out several potential explanations for this anisotropy and propose that our results may be understood in the context of the anisotropic altermagnetic ordering of Ba\(_2\)CoGe\(_2\)O\(_7\).
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Correlations drive the attosecond response of strongly-correlated insulators
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-02-03 20:00 EST
Romain Cazali, Amina Alic, Matthieu Guer, Christopher J. Kaplan, Fabien Lepetit, Olivier Tcherbakoff, Stéphane Guizard, Angel Rubio, Nicolas Tancogne-Dejean, Gheorghe S. Chiuzbăian, Romain Géneaux
Attosecond spectroscopy of materials has provided invaluable insight into light-driven coherent electron dynamics. However, attosecond spectroscopies have so far been focused on weakly-correlated materials. As a result, the behavior of strongly-correlated systems is largely unknown at sub- to few-femtosecond timescales, even though it is typically the realm at which electron-electron interactions operate. Here we conduct attosecond-resolved experiments on the correlated insulator nickel oxide, and compare its response to a common band insulator, revealing fundamentally different behaviors. The results, together with state-of-the art time-dependent \(\textit{ab initio}\) calculations, show that the correlated system response is governed by a laser-driven quench of electron correlations. The evolution of the on-site electronic interaction is measured here at its natural timescale, marking the first direct measurement of Hubbard \(U\) renormalization in NiO. It is found to take place within a few femtoseconds, after which structural changes slowly start to take place. The resulting picture sheds light on the entire light-induced response of a strongly-correlated system, from attosecond to long-lived effects.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Hydrodynamic attractor in periodically driven ultracold quantum gases
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-02-03 20:00 EST
Aleksas Mazeliauskas, Tilman Enss
Hydrodynamic attractors are a universal phenomenon of strongly interacting systems that describe the hydrodynamic-like evolution far from local equilibrium. In particular, the rapid hydrodynamization of the Quark-Gluon Plasma is behind the remarkable success of hydrodynamic models of high-energy nuclear collisions. So far, hydrodynamic attractors have been explored only in systems undergoing monotonic expansion, such as Bjorken flow. We demonstrate that a system with an oscillating isotropic expansion exhibits a novel cyclic attractor behavior. This phenomenon can be investigated in ultracold quantum gases with externally modulated scattering length, offering a new avenue for experimentally discovering hydrodynamic attractors.
Quantum Gases (cond-mat.quant-gas), High Energy Physics - Phenomenology (hep-ph), Nuclear Theory (nucl-th)
8 pages, 5 figures
Strong geometry dependence of the X-ray Thomson Scattering Spectrum in single crystal silicon
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
Thomas Gawne, Zhandos A. Moldabekov, Oliver S. Humphries, Karen Appel, Carsten Baehtz, Victorien Bouffetier, Erik Brambrink, Attila Cangi, Celine Crépisson, Sebastian Göde, Zuzana Konôpková, Mikako Makita, Mikhail Mishchenko, Motoaki Nakatsutsumi, Lisa Randolph, Sebastian Schwalbe, Jan Vorberger, Ulf Zastrau, Tobias Dornheim, Thomas R. Preston
We report on results from an experiment at the European XFEL where we measured the x-ray Thomson scattering (XRTS) spectrum of single crystal silicon with ultrahigh resolution. Compared to similar previous experiments, we consider a more complex scattering setup, in which the scattering vector changes orientation through the crystal lattice. In doing so, we are able to observe strong geometric dependencies in the inelastic scattering spectrum of silicon at low scattering angles. Furthermore, the high quality of the experimental data allows us to benchmark state-of-the-art TDDFT calculations, and demonstrate TDDFT's ability to accurately predict these geometric dependencies. Finally, we note that this experimental data was collected at a much faster rate than another recently reported dataset using the same setup, demonstrating that ultrahigh resolution XRTS data can be collected in more general experimental scenarios.
Materials Science (cond-mat.mtrl-sci), Plasma Physics (physics.plasm-ph)
Top eigenvalue statistics of diluted Wishart matrices
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-03 20:00 EST
Barak Budnick, Preben Forer, Pierpaolo Vivo, Sabrina Aufiero, Silvia Bartolucci, Fabio Caccioli
Using the replica method, we compute analytically the average largest eigenvalue of diluted covariance matrices of the form \(\mathbf{J} = \mathbf{X}^T \mathbf{X}\), where \(\mathbf{X}\) is a \(N\times M\) sparse data matrix, in the limit of large \(N,M\) with fixed ratio. We allow for random non-zero weights, provided they lead to an isolated largest eigenvalue. By formulating the problem as the optimisation of a quadratic Hamiltonian constrained to the \(N\)-sphere at low temperatures, we derive a set of recursive distributional equations for auxiliary probability density functions, which can be efficiently solved using a population dynamics algorithm. The average largest eigenvalue is identified with a Lagrange parameter that governs the convergence of the algorithm. We find excellent agreement between our analytical results and numerical results obtained from direct diagonalisation.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Mathematical Physics (math-ph)
24 pages, 3 figures
Statistical Physics of Deep Neural Networks: Generalization Capability, Beyond the Infinite Width, and Feature Learning
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-02-03 20:00 EST
Deep Neural Networks (DNNs) excel at many tasks, often rivaling or surpassing human performance. Yet their internal processes remain elusive, frequently described as "black boxes." While performance can be refined experimentally, achieving a fundamental grasp of their inner workings is still a challenge. Statistical Mechanics has long tackled computational problems, and this thesis applies physics-based insights to understand DNNs via three complementary approaches. First, by averaging over data, we derive an asymptotic bound on generalization that depends solely on the size of the last layer, rather than on the total number of parameters -- revealing how deep architectures process information differently across layers. Second, adopting a data-dependent viewpoint, we explore a finite-width thermodynamic limit beyond the infinite-width regime. This leads to: (i) a closed-form expression for the generalization error in a finite-width one-hidden-layer network (regression task); (ii) an approximate partition function for deeper architectures; and (iii) a link between deep networks in this thermodynamic limit and Student's t-processes. Finally, from a task-explicit perspective, we present a preliminary analysis of how DNNs interact with a controlled dataset, investigating whether they truly internalize its structure -- collapsing to the teacher -- or merely memorize it. By understanding when a network must learn data structure rather than just memorize, it sheds light on fostering meaningful internal representations. In essence, this thesis leverages the synergy between Statistical Physics and Machine Learning to illuminate the inner behavior of DNNs.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Machine Learning (cs.LG)
PhD thesis (200 pages), divided into four separate chapters, each of which can be read independently. Some of the material presented has previously appeared in works available on arXiv under the following identifiers: 2209.04882 and 2201.11022
A Metal-Insulator Transition of the Buried MnO2 Monolayer in Complex Oxide Heterostructure
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
Heng-Jui Liu, Jheng-Cyuan Lin, Yue-Wen Fang, Jing-Ching Wang, Bo-Chao Huang, Xiang Gao, Rong Huang, Philip R. Dean, Peter D. Hatton, Yi-Ying Chin, Hong-Ji Lin, Chien-Te Chen, Yuichi Ikuhara, Ya-Ping Chiu, Chia-Seng Chang, Chun-Gang Duan, Qing He, Ying-Hao Chu
Functionalities in crystalline materials are determined by 3-dimensional collective interactions of atoms. The confinement of dimensionality in condensed matter provides an exotic research direction to understand the interaction of atoms, thus can be used to tailor or create new functionalities in material systems. In this study, a 2-dimensional transition metal oxide monolayer is constructed inside complex oxide heterostructures based on the theoretical predictions. The electrostatic boundary conditions of oxide monolayer in the heterostructure is carefully designed to tune the chemical, electronic, and magnetic states of oxide monolayer. The challenge of characterizing such an oxide monolayer is overcome by a combination of transmission electron microscopy, x-ray absorption spectroscopy, cross-sectional scanning tunneling microscopy, and electrical transport measurements. An intriguing metal-insulator transition associated with a magnetic transition is discovered in the MnO2 monolayer. This study paves a new route to understand the confinement of dimensionality and explore new intriguing phenomena in condensed matters.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Applied Physics (physics.app-ph)
23 pages, 6 figures
Adv. Mater., 28: 9142-9151(2016)
Solid-state Synapse Based on Magnetoelectrically Coupled Memristor
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
Weichuan Huang, Yue-Wen Fang, Yuewei Yin, Bobo Tian, Wenbo Zhao, Chuangming Hou, Chao Ma, Qi Li, Evgeny Y. Tsymbal, Chun-Gang Duan, Xiaoguang Li
Brain-inspired computing architectures attempt to emulate the computations performed in the neurons and the synapses in human brain. Memristors with continuously tunable resistances are ideal building blocks for artificial synapses. Through investigating the memristor behaviors in a La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 multiferroic tunnel junction, it was found that the ferroelectric domain dynamics characteristics are influenced by the relative magnetization alignment of the electrodes, and the interfacial spin polarization is manipulated continuously by ferroelectric domain reversal, enriching our understanding of the magnetoelectric coupling fundamentally. This creates a functionality that not only the resistance of the memristor but also the synaptic plasticity form can be further manipulated, as demonstrated by the spike-timing-dependent plasticity investigations. Density functional theory calculations are carried out to describe the obtained magnetoelectric coupling, which is probably related to the Mn-Ti intermixing at the interfaces. The multiple and controllable plasticity characteristic in a single artificial synapse, to resemble the synaptic morphological alteration property in a biological synapse, will be conducive to the development of artificial intelligence.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el), Applied Physics (physics.app-ph)
5 figures, 20 pages
ACS Applied Materials & Interfaces 2018, 10, 6, 5649-5656
Reactive Fluid Ferroelectrics: A Gateway to the Next Generation of Ferroelectric Liquid Crystalline Polymer Networks
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-02-03 20:00 EST
Stuart R Berrow, Jordan Hobbs, Calum J Gibb
Herein we report the first examples of reactive mesogenic materials (RMs) which exhibit fluid ferroelectric order based on the recently discovered ferroelectric nematic (NF) phase. We term these materials NF RMs and they provide the first steps towards the next generation of ferroelectric liquid crystalline polymer networks. We report the chemical synthesis and characterisation of the liquid crystalline properties of these materials, demonstrating that they have the lowest longitudinal molecular dipole moments of any reported NF material of 7.39 D. We go on to demonstrate a potential use case of this new class of reactive material through the polymer stabilisation of a matrix which exhibits the NF phase, increasing the phase range of the ferroelectric phase from 75 °C to 120 °C. The NF RMs reported herein are an exciting step forward in ferroelectric liquid crystal research, demonstrating that reactive NF materials are achievable, allowing for the future development of liquid crystalline ferroelectric networks, elastomers and polymers.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft)
Molecular details and free energy barriers of ion de-coordination at elevated salinity and pressure
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-03 20:00 EST
Nathanael S. Schwindt, Razi Epsztein, Anthony P. Straub, Michael R. Shirts
Ion dehydration has been shown to strongly influence separation performance in membrane systems and ion transport in nanoscale channels. It is especially important for membrane-based brine treatment, which is limited by high pressures and concentrations. However, the molecular details and drivers of ion dehydration in membranes are not well understood, in particular under relevant conditions for membrane operation. In this study, we estimated the dehydration free energies for a range of different ions at high pressure and salinity relevant to brine treatment using molecular simulation. In order to more clearly interpret these results, we developed a procedure to unambiguously estimate these free energies as a function of discrete-valued coordination number. We also proposed alternatives to the coordination number as geometrical constraints for traversing nanoscale constrictions, such as the maximum cross-sectional area of the complexed ion, and calculated the free energy of dehydration as a function of these constraints. We show that high operating pressures do not significantly change cation hydration shell stability nor the shell size, while high ionic concentrations lower the free energy barrier to reduce the cation coordination number. High concentration introduces many ion pairing events, which contribute to the lower barrier. We find that anion dehydration free energies are largely unaffected by these conditions, only showing a small increase in free energy at high pressure. We propose strategies to improve ion-ion selectivity by leveraging the effects of elevated pressure and salinity on ion dehydration.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Chemical Physics (physics.chem-ph)
39 pages, 9 figures; Supporting Information 24 pages, 20 figures
Mechanical Properties of the Meninges: Large Language Model Assisted Systematic Review of over 25,000 Studies
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-02-03 20:00 EST
Brandon P. Chelstrom, Maciej P. Polak, Dane Morgan, Corinne R. Henak
Accurate constitutive models and corresponding mechanical property values for the meninges are important for predicting mechanical damage to brain tissue due to traumatic brain injury. The meninges are often oversimplified in current finite element (FE) head models due to their complex anatomy and spatially-variant mechanical behavior. This study performed a systematic review (SR) on the mechanical properties of each individual layer of the meninges to obtain benchmark data for FE modeling and to identify gaps in the current literature. Relevant studies were filtered through three stages: a broad initial search filter, a large language model classifier, and manual verification by a human reviewer. Out of over 25,000 studies initially considered, this review ultimately included 47 studies on the dura mater, 8 on the arachnoid mater, and 7 on the pia mater, representing the largest and most comprehensive SR on the mechanical properties of the meninges. Each layer was found to exhibit nonlinear rate dependence that varies with species, age, location, and orientation. This study revealed that the elastic modulus of pia mater most often used in simplified linear elastic FE models is likely underestimated by an order of magnitude and fails to consider directional dependence. Future studies investigating the mechanical properties of the meninges should focus on a wider range of loading rates as well as age effects for the arachnoid mater and pia mater, as these features are relatively understudied and expected to affect the fidelity of FE predictions.
Soft Condensed Matter (cond-mat.soft), Medical Physics (physics.med-ph)
56 pages including supplemental. One graphical abstract, 6 main text figures, 2 supplemental figures
Turbulence: A Nonequilibrium Field Theory
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-02-03 20:00 EST
Tools of quantum and statistical field theories have ben successfully ported to turbulence. Here, we review the key results of turbulence field theory. Thermalized spectrally-truncated Euler equation is described by , in which the equipartitioned Fourier modes generate zero energy flux. In contrast, modelling of hydrodynamic turbulence (HDT), which has small viscosity, requires . In HDT, the viscosity is renormalized using field theory that leads to wavenumber-dependent viscosity and energy spectrum. Field theory calculations also yields nonzero energy flux for HDT. These field theory computations have been generalized to other systems, e.g., passive scalar and magnetohydrodynamics. In this review, we cover these aspects, along with a brief coverage of weak turbulence and intermittency.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th), Chaotic Dynamics (nlin.CD), Fluid Dynamics (physics.flu-dyn)
51 pages
Two-site Kitaev sweet spots evolving into topological islands
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-02-03 20:00 EST
Rodrigo A. Dourado, J. Carlos Egues, Poliana H. Penteado
Artificial Kitaev chains based on arrays of quantum dots are promising platforms for realizing Majorana Bound States (MBSs). In a two-site Kitaev chain, it is possible to find these non-Abelian zero-energy excitations at certain points in parameter space (sweet spots). These states, commonly referred to as Poor man's Majorana bound states (PMMs), are challenging to find and stabilize experimentally. In this work, we investigate the evolution of the sweet spots as we increase the number of sites of the Kitaev chain. To this end, we use the Bogoliubov-de Gennes representation to study the excitations of the system, and the scattering matrix and Green functions formalisms to calculate the zero-bias conductance. Our results show that the sweet spots evolve into a region that grows bigger and becomes gradually more protected as the number of sites \(N\) increases. Due to the protection of the MBSs, we refer to this region as a topological island. We obtain similar results by considering a realistic spinful model with finite magnetic fields in a chain of normal-superconducting quantum dots. For long chains, \(N \geq 20\), we show the emergence of strictly zero-energy plateaus robust against disorder. Finally, we demonstrate that the topological islands can be observed by performing conductance measurements via a quantum dot side-coupled to the Kitaev chain. Our work shows that the fine-tuning required to create and detect PMMs in a 2-site Kitaev chain is significantly relaxed as the length of the chain increases and details how PMMs evolve into MBSs. Our results are consistent with experimental reports for 2 and 3-site chains.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)