CMP Journal 2025-05-26
Statistics
Nature: 1
Nature Physics: 1
arXiv: 63
Nature
Scaling and logic in the color code on a superconducting quantum processor
Original Paper | Computer science | 2025-05-25 20:00 EDT
N. Lacroix, A. Bourassa, F. J. H. Heras, L. M. Zhang, J. Bausch, A. W. Senior, T. Edlich, N. Shutty, V. Sivak, A. Bengtsson, M. McEwen, O. Higgott, D. Kafri, J. Claes, A. Morvan, Z. Chen, A. Zalcman, S. Madhuk, R. Acharya, L. Aghababaie Beni, G. Aigeldinger, R. Alcaraz, T. I. Andersen, M. Ansmann, F. Arute, K. Arya, A. Asfaw, J. Atalaya, R. Babbush, B. Ballard, J. C. Bardin, A. Bilmes, S. Blackwell, J. Bovaird, D. Bowers, L. Brill, M. Broughton, D. A. Browne, B. Buchea, B. B. Buckley, T. Burger, B. Burkett, N. Bushnell, A. Cabrera, J. Campero, H.-S. Chang, B. Chiaro, L.-Y. Chih, A. Y. Cleland, J. Cogan, R. Collins, P. Conner, W. Courtney, A. L. Crook, B. Curtin, S. Das, S. Demura, L. De Lorenzo, A. Di Paolo, P. Donohoe, I. Drozdov, A. Dunsworth, A. Eickbusch, A. Moshe Elbag, M. Elzouka, C. Erickson, V. S. Ferreira, L. Flores Burgos, E. Forati, A. G. Fowler, B. Foxen, S. Ganjam, G. Garcia, R. Gasca, É. Genois, W. Giang, D. Gilboa, R. Gosula, A. Grajales Dau, D. Graumann, A. Greene, J. A. Gross, T. Ha, S. Habegger, M. Hansen, M. P. Harrigan, S. D. Harrington, S. Heslin, P. Heu, R. Hiltermann, J. Hilton, S. Hong, H.-Y. Huang, A. Huff, W. J. Huggins, E. Jeffrey, Z. Jiang, X. Jin, C. Joshi, P. Juhas, A. Kabel, H. Kang, A. H. Karamlou, K. Kechedzhi, T. Khaire, T. Khattar, M. Khezri, S. Kim, P. V. Klimov, B. Kobrin, A. N. Korotkov, F. Kostritsa, J. Mark Kreikebaum, V. D. Kurilovich, D. Landhuis, T. Lange-Dei, B. W. Langley, P. Laptev, K.-M. Lau, J. Ledford, K. Lee, B. J. Lester, L. Le Guevel, W. Yan Li, Y. Li, A. T. Lill, W. P. Livingston, A. Locharla, E. Lucero, D. Lundahl, A. Lunt, A. Maloney, S. Mandrà, L. S. Martin, O. Martin, C. Maxfield, J. R. McClean, S. Meeks, A. Megrant, K. C. Miao, R. Molavi, S. Molina, S. Montazeri, R. Movassagh, C. Neill, M. Newman, A. Nguyen, M. Nguyen, C.-H. Ni, M. Y. Niu, L. Oas, W. D. Oliver, R. Orosco, K. Ottosson, A. Pizzuto, R. Potter, O. Pritchard, C. Quintana, G. Ramachandran, M. J. Reagor, R. Resnick, D. M. Rhodes, G. Roberts, E. Rosenberg, E. Rosenfeld, E. Rossi, P. Roushan, K. Sankaragomathi, H. F. Schurkus, M. J. Shearn, A. Shorter, V. Shvarts, S. Small, W. Clarke Smith, S. Springer, G. Sterling, J. Suchard, A. Szasz, A. Sztein, D. Thor, E. Tomita, A. Torres, M. Mert Torunbalci, A. Vaishnav, J. Vargas, S. Vdovichev, G. Vidal, C. Vollgraff Heidweiller, S. Waltman, J. Waltz, S. X. Wang, B. Ware, T. Weidel, T. White, K. Wong, B. W. K. Woo, M. Woodson, C. Xing, Z. Jamie Yao, P. Yeh, B. Ying, J. Yoo, N. Yosri, G. Young, Y. Zhang, N. Zhu, N. Zobrist, H. Neven, P. Kohli, A. Davies, S. Boixo, J. Kelly, C. Jones, C. Gidney, K. J. Satzinger
Quantum error correction [1-4] is essential for bridging the gap between the error rates of physical devices and the extremely low error rates required for quantum algorithms. Recent error-correction demonstrations on superconducting processors [5-8] have focused primarily on the surface code [9], which offers a high error threshold but poses limitations for logical operations. The color code [10] enables more efficient logic, but it requires more complex stabilizer measurements and decoding. Measuring these stabilizers in planar architectures like superconducting qubits is challenging, and realizations of color codes [11-19] have not addressed performance scaling with code size on any platform. Here, we present a comprehensive demonstration of the color code on a superconducting processor [8]. Scaling the code distance from three to five suppresses logical errors by a factor of Λ3/5 = 1.56(4). Simulations indicate this performance is below the threshold of the color code, and the color code may become more efficient than the surface code following modest device improvements. We test transversal Clifford gates with logical randomized benchmarking [20] and inject magic states [21], a key resource for universal computation, achieving fidelities exceeding 99 % with post-selection. Finally, we teleport logical states between color codes using lattice surgery [22]. This work establishes the color code as a compelling research direction to realize fault-tolerant quantum computation on superconducting processors in the near future.
Computer science, Quantum information
Nature Physics
Optomechanical self-organization in a mesoscopic atom array
Original Paper | Atomic and molecular interactions with photons | 2025-05-25 20:00 EDT
Jacquelyn Ho, Yue-Hui Lu, Tai Xiang, Cosimo C. Rusconi, Stuart J. Masson, Ana Asenjo-Garcia, Zhenjie Yan, Dan M. Stamper-Kurn
Increasing the number of particles in a system often leads to qualitative changes in its properties, such as breaking of symmetries and the appearance of phase transitions. This renders a macroscopic system fundamentally different from its individual microscopic constituents. Lying between these extremes, mesoscopic systems exhibit microscopic fluctuations that influence behaviour on longer length scales, leading to critical phenomena and dynamics. Therefore, tracing the properties of well-controlled mesoscopic systems can help bridge the gap between an exact description of few-body microscopic systems and the emergent description of many-body systems. Here we explore the mesoscopic signatures of an optomechanical self-organization phase transition using arrays of cold atoms inside an optical cavity. By precisely engineering atom-cavity interactions, we reveal how critical behaviour depends on the atom number, identify characteristic dynamical behaviours in the self-organized regime and observe a finite optomechanical susceptibility at the critical point. These findings advance our understanding of particle-number- and time-resolved properties of phase transitions in mesoscopic systems.
Atomic and molecular interactions with photons, Phase transitions and critical phenomena, Quantum simulation, Ultracold gases
arXiv
Lieb-Mattis ordering theorem of electronic energy levels in the thermodynamic limit
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-26 20:00 EDT
Maunel Calixto, Alberto Mayorgas, Julio Guerrero
Lieb-Mattis theorem orders the lowest-energy states of total spin $ s$ of a system of $ P$ interacting fermions. We generalize these predictions to fermionic mixtures of $ P$ particles with more than $ N=2$ spinor components/species in the thermodynamic limit $ P\to\infty$ . The lowest-energy state inside each permutation symmetry sector $ h$ , arising in the $ P$ -fold tensor product decomposition, is well approximated by a U$ (N)$ coherent (quasi-classical, variational) state, specially in the limit $ P\to\infty$ . In particular, the ground state of the system belongs the most symmetric (dominant Young tableau $ h_0$ ) configuration. We exemplify our construction with the $ N=3$ level Lipkin-Meshkov-Glick model, with a previous motivation on pairing correlations and U$ (N)$ -invariant quantum Hall ferromagnets. In the limit $ P\to\infty$ , each lowest-energy state within each permutation symmetry sector $ h$ undergoes a quantum phase transition for a critical value $ \lambda_c(h)$ of the exchange coupling constant $ \lambda$ , depending on $ h$ . This generalizes standard quantum phase transitions and their phase diagrams corresponding to the ground state belonging to the most symmetric sector $ h_0$ .
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
16 pages, 3 figures, 2 gif as ancillary files
Unconventional tunnel magnetoresistance scaling with altermagnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-26 20:00 EDT
Zongmeng Yang, Xingyue Yang, Jianhua Wang, Rui Peng, Lee Ching Hua, Lay Kee Ang, Jing Lu, Yee Sin Ang, Shibo fang
In conventional magnetic tunnel junctions (MTJs), the tunnel magnetoresistance (TMR) typically increases with barrier thickness as electron transmission in the antiparallel configuration decays faster than that of the parallel configuration. In this work, we reveal an anomalous scaling effect in altermagnetic tunnel junctions (AMTJs), where the TMR decreases anomalously with an increasing barrier thickness. The anomalous scaling originates from the overlapping spin-split branches form a transmission path that cannot be suppressed in the antiparallel state. Such phenomena is explained by adouble-barrier model and is further demonstrated using ab initio quantum transport simulations in 2D V2Te2O/Cr2Se2O/V2Te2O-based AMTJ, where the TMR anomalously decreases from 220% to 40% as the layer number of Cr2Se2O increases from 1 to 5. Our work identifies a peculiar unexpected transport characteristic of AMTJ, providing a fundamental limit on AMTJ device design and illustrating the potential optimal design of AMTJ at the ultrascaled monolayer limit.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Resolving Intervalley Gaps and Many-Body Resonances in Moiré Superconductor
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-26 20:00 EDT
Hyunjin Kim, Gautam Rai, Lorenzo Crippa, Dumitru Călugăru, Haoyu Hu, Youngjoon Choi, Lingyuan Kong, Eli Baum, Yiran Zhang, Ludwig Holleis, Kenji Watanabe, Takashi Taniguchi, Andrea F. Young, B. Andrei Bernevig, Roser Valentí, Giorgio Sangiovanni, Tim Wehling, Stevan Nadj-Perge
Magic-angle twisted multilayer graphene stands out as a highly tunable class of moiré materials that exhibit strong electronic correlations and robust superconductivity. However, understanding the relations between the low-temperature superconducting phase and the preceding correlated phases established at higher temperatures remains a challenge. Here, we employ scanning tunneling microscopy and spectroscopy to track the formation sequence of correlated phases established by the interplay of dynamic correlations, intervalley coherence, and superconductivity in magic-angle twisted trilayer graphene (MATTG). We discover the existence of two well-resolved gaps pinned at the Fermi level within the superconducting doping range. While the outer gap, previously associated with pseudogap phase, persists at high temperatures and magnetic fields, the newly revealed inner gap is more fragile in line with superconductivity MATTG transport experiments. Andreev reflection spectroscopy taken at the same location confirms a clear trend that closely follows the doping behaviour of the inner gap, and not the outer one. Moreover, spectroscopy taken at nanoscale domain boundaries further corroborates the contrasting behavior of the two gaps, with the inner gap remaining resilient to structural variations, as expected from the finite superconducting coherence length. By comparing our findings with recent topological heavy-fermion models, we identify that the outer gap originates from the splitting of the Abrikosov-Suhl-Kondo resonance due to the breaking of the valley symmetry arising from correlation-driven effects. Our results suggest an intricate but tractable hierarchy of correlated phases in twisted multilayer graphene.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
main text, extended data and supplementary information
Engineering Altermagnetism via Layer Shifts and Spin Order in Bilayer MnPS$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
J. W. González, T. Brumme, E. Suárez Morell, A. M. León
We investigate how stacking configuration and magnetic ordering determine the magnetic phases of bilayer MnPS$ _3$ , using density-functional theory and spin-Laue symmetry analysis. While monolayer MnPS$ _3$ is a collinear antiferromagnet with no spin splitting, our calculations show that the bilayer can host either Type II (AFM) or Type III (altermagnetic) phases depending sensitively on stacking and spin alignment. We focus on two representative stackings: AA, where the top layer sits directly above the bottom one, and AA$ ^\prime$ , its inversion-symmetric counterpart obtained by reflecting one layer about the out-of-plane axis. For each geometry, we consider two collinear spin alignments, $ \uparrow\downarrow/\uparrow\downarrow$ and $ \uparrow\downarrow/\downarrow\uparrow$ , and explore lateral displacements to sample the full stacking landscape. Our results show that magnetic order and interlayer symmetry breaking jointly enable momentum-dependent spin polarization without net magnetization. These findings highlight stacking and spin alignment as coupled symmetry control parameters for engineering altermagnetism in van der Waals magnets, paving the way toward tunable spintronic functionality.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 6 figures
Tunable photogating in a molecular aggregate coupled graphene phototransistor
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-26 20:00 EDT
Abhinav Raina, Maurizio Sanfilippo, Chang-Ki Moon, Manuel Neubauer, Klaus Meerholz, Malte C. Gather, Klas Lindfors
We present a graphene photodetector coupled to a layer of aggregated organic semiconductor. A graphene phototransistor is covered with a thin film of merocyanine molecules. The aggregation of the molecular layer can be controlled by the deposition parameters and post-deposition annealing to obtain films ranging from amorphous to a highly aggregated state. The molecular layer has a uniaxial structure with excitonic transitions whose transition dipole moments are well defined. The presence of the molecular layer results in an enormous increase in the response of the phototransistor. We further demonstrate that the signal-enhancement is due to p-photodoping of the graphene. The spectroscopic photoresponse suggests that the photodoping via monomers and molecular aggregates takes place differently. Our photodetector is a platform to study the influence of molecular aggregation and order on charge transport processes between aggregated organic semiconductors and two-dimensional materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
Advancing Excited-State Properties of 2D Materials Using a Dielectric-Dependent Hybrid Functional
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Arghya Ghosh, Subrata Jana, Manoar Hossain, Dimple Rani, Szymon Śmiga, Prasanjit Samal
Predicting accurate band gaps and optical properties of lower-dimensional materials, including two-dimensional van der Waals (vdW) materials and their heterostructures, remains a challenge within density functional theory (DFT) due to their unique screening compared to their bulk counterparts. Additionally, accurate treatment of the dielectric response is crucial for developing and applying screened-exchange dielectric-dependent range-separated hybrid functionals (SE-DD-RSH) for vdW materials. In this work, we introduce a SE-DD-RSH functional to the 2D vdW materials like MoS2, WS2, hBN, black phosphorus (BP), and \b{eta}-InSe. By accounting for in-plane and out-of-plane dielectric responses, our method achieves accuracy comparable to advanced many-body techniques like G0 W0 and BSE@G0 W0 at a lower computational cost. We demonstrate improved band gap predictions and optical absorption spectra for both bulk and layered structures, including some heterostructures like MoS2/WS2 . This approach offers a practical and precise tool for exploring electronic and optical phenomena in 2D materials, paving the way for efficient computational studies of layered systems.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
21 pages 7 Figures
Self-consistent layer-projected scissors operator for band structures of complex 2D van der Waals materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Dario A. Leon, Mikael Kuisma, Mikkel Ohm Sauer, Jakob K. Svaneborg, Mark K. Svendsen, Stefano Americo, Kristian Berland, Jens Jørgen Mortensen, Kristian S. Thygesen
We introduce a computationally efficient method to calculate the quasiparticle (QP) band structure of general van der Waals (vdW) heterostructures. A layer-projected scissors (LAPS) operator, which depends on the one-body density matrix, is added to the density functional theory (DFT) Hamiltonian. The LAPS operator corrects the band edges of the individual layers for self-energy effects (both intralayer and interlayer) and unphysical strain fields stemming from the use of model supercells. The LAPS operator is treated self-consistently whereby charge redistribution and interlayer hybridization occurring in response to the band energy corrections are properly accounted for. We present several examples illustrating both the qualitative and quantitative performance of the method, including MoS$ _2$ films with up to 20 layers, bilayer MoS$ _2$ in an electric field, lattice-matched MoS$ _2$ /WS$ _2$ and MoSe$ _2$ /WSe$ _2$ bilayers, and MoSe$ _2$ /WS$ _2$ moiré structures. Our work opens the way for predictive modeling of electronic, optical, and topological properties of complex and experimentally relevant vdW materials.
Materials Science (cond-mat.mtrl-sci)
Promoted current-induced spin polarization in inversion symmetry broken topological insulator thin films
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-26 20:00 EDT
Maryam Heydari, Hanieh Moghaddasi, Mir Vahid Hosseini, Mehdi Askari
We theoretically investigate current-induced spin polarization in disordered topological insulator thin films with broken inversion symmetry under an applied in-plane electric field. Utilizing the Kubo formalism within the self-consistent Born approximation, and incorporating vertex corrections to account for multiple scattering events, we analyze how disorder, chemical potential, the electrostatic potential difference between the top and bottom surfaces, and momentum-dependent hybridization affect the spin susceptibility. Our results reveal that the spin susceptibility exhibits nonzero values within a finite range around a zero gap, and this range broadens as the chemical potential increases. A higher hybridization strength induces asymmetry in the spin response, and a stronger potential difference, breaking inversion symmetry, significantly enhances polarization, a trend attributable to band inversion that is further refined by vertex corrections. These findings provide a theoretical framework for tuning spin-charge conversion in topological thin films, with implications for spintronic device applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
26 pages, 10 figures
Stochastic Heat Engine Using a Single Brownian Ellipsoid
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-26 20:00 EDT
Optical tweezers can confine position as well as orientation of a Brownian particle by simultaneously exerting restoring force and torque on it. Here we have proposed the theoretical model of a microscopic Stirling engine, using a passive Brownian ellipsoid as its working substance. The position and the orientation degrees of freedom (DoF) of the ellipsoid in two dimensions (2D), both being confined harmonically by the tweezers, are coupled to a hot and a cold thermal bath time-periodically. The stiffness of the force confinement is also time-periodic such that it resembles a piston-like protocol which drives the Brownian ellipsoid through the strokes of a Stirling cycle. The ellipsoid takes heat from the hot bath and partially converts it into useful thermodynamic work. The extracted work and input heat shows explicit dependence on the shape of the working substance as well as its orientational bias. The operational characteristics of the anisotropic Stirling engine is analyzed using the variance in work and efficiency (in the quasi-static regime), where the latter is bounded by both the Carnot limit as well as the isotropic benchmark. Several ways have been proposed to yield maximum efficiency at a minimum fluctuation in the output. The dissipative coupling between the position and orientation of the ellipsoid, that arises due to its spherical-asymmetry (or, shape anisotropy) and a finite mean orientation, plays an important role to optimize the engine characteristics. Finally, we have analytically explored the slightly anisotropic regime, where the coupling is linearized by suitably tuning the system parameters. The average extracted work has also been calculated in this case, which shows an excellent agreement with the numerical results of the fully anisotropic system, when subjected to the stipulated range of parameters.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
A few revisions may be necessary. Comments are welcome
Non-excitonic mechanism for electronic and structural phase transitions in Ta2Ni(Se,S)5
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Weichen Tang, Zhenglu Li, Cheng Chen, Yu He, Steven G. Louie
We present a first-principles study based on density functional theory (DFT) on the electronic and structural properties of Ta2NiSe5, a layered transition metal chalcogenide that has been considered as a possible candidate for an excitonic insulator. Our systematic DFT results however provide a non-excitonic mechanism for the experimentally observed electronic and structural phase transitions in Ta2NiSe5, in particular explaining why sulfur substitution of selenium reduces the distortion angle in the low-temperature phase and potassium dosing closes the gap in the electronic structure. Moreover, the calculations show that these two effects couple to each other. Further, our first-principles calculations predict several changes in both the crystal structure and electronic structure under the effects of uniform charge dosing and uniaxial strain, which could be tested experimentally.
Materials Science (cond-mat.mtrl-sci)
Quantum geometric origin of Meissner effect and superfluid weight marker
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-26 20:00 EDT
The momentum space of conventional superconductors is recently recognized to possess a quantum metric defined from the overlap of filled quasihole states at neighboring momenta. For multiband superconductors with arbitrary intraband and interband $ s$ -wave pairing, we elaborate that their superfluid weight in London equations is given by the momentum integration of the elements of quantum metric times the quasiparticle energy, indicating the quantum geometric origins of Meissner effect and vortex state. The momentum integration of the quantum metric further yields a spread of quasihole Wannier functions that characterizes the stability of the superconducting state. Our formalism allows the diamagnetic response of conventional superconductors to be mapped to individual lattice sites as a superfluid weight marker, which can incorporate the effect of disorder through self-consistently solving the Bogoliubov-de Gennes equations. Using single-band $ s$ -wave superconductors in 2D and 3D as examples, our marker reveals a diamagnetic current that becomes turbulent in the presence of nonmagnetic impurities, and the increase of London penetration depth by disorder that is consistent with experiments.
Superconductivity (cond-mat.supr-con)
9 pages, 4 figures
Cavity-Altered Superconductivity
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-26 20:00 EDT
Itai Keren (1), Tatiana A. Webb (1), Shuai Zhang (1), Jikai Xu (1), Dihao Sun (1), Brian S. Y. Kim (1), Dongbin Shin (2 and 3), Songtian S. Zhang (1), Junhe Zhang (1), Giancarlo Pereira (1), Juntao Yao (4 and 5), Takuya Okugawa (1 and 2), Marios H. Michael (2), James H. Edgar (6), Stuart Wolf (7), Matthew Julian (7)Rohit P. Prasankumar (7), Kazuya Miyagawa (8), Kazushi Kanoda (9 and 10 and 8), Genda Gu (4), Matthew Cothrine (11), David Mandrus (11), Michele Buzzi (2), Andrea Cavalleri (2 and 12), Cory R. Dean (1), Dante M. Kennes (2 and 13), Andrew J. Millis (1 and 14), Qiang Li (4 and 15), Michael A. Sentef (16 and 2), Angel Rubio (2 and 17), Abhay N. Pasupathy (1 and 4), Dmitri N. Basov (1) ((1) Department of Physics, Columbia University, (2) Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, (3) Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), (4) Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory, (5) Department of Materials Science and Chemical Engineering, Stony Brook University, (6) Tim Taylor Department of Chemical Engineering, Kansas State University, (7) Deep Science Fund, Intellectual Ventures, (8) Department of Applied Physics, The University of Tokyo, (9) Max Planck Institute for Solid State Research, Stuttgart (10) Physics Institute, University of Stuttgart, (11) Department of Materials Science and Engineering, University of Tennessee, (12) Department of Physics, University of Oxford, (13) Institut für Theorie der Statistischen Physik, RWTH Aachen, (14) Center for Computational Quantum Physics, The Flatiron Institute, (15) Department of Physics and Astronomy, Stony Brook University, (16) Institute for Theoretical Physics and Bremen Center for Computational Materials Science, University of Bremen, (17) Initiative for Computational Catalysts, The Flatiron Institute)
Is it feasible to alter the ground state properties of a material by engineering its electromagnetic environment? Inspired by theoretical predictions, experimental realizations of such cavity-controlled properties without optical excitation are beginning to emerge. Here, we devised and implemented a novel platform to realize cavity-altered materials. Single crystals of hyperbolic van der Waals (vdW) compounds provide a resonant electromagnetic environment with enhanced density of photonic states and superior quality factor. We interfaced hexagonal boron nitride (hBN) with the molecular superconductor $ \kappa$ -(BEDT-TTF)$ _2$ Cu[N(CN)$ _2$ ]Br ($ \kappa$ -ET). The frequencies of infrared (IR) hyperbolic modes of hBN match the IR-active carbon-carbon stretching molecular resonance of ($ \kappa$ -ET) implicated in superconductivity. Nano-optical data supported by first-principles molecular Langevin dynamics simulations confirm resonant coupling between the hBN hyperbolic cavity modes and the carbon-carbon stretching mode in ($ \kappa$ -ET). Meissner effect measurements via magnetic force microscopy demonstrate a strong suppression of superfluid density near the hBN/($ \kappa$ -ET) interface. Non-resonant control heterostructures, including RuCl$ _3$ /($ \kappa$ -ET) and hBN/$ \text{Bi}_2\text{Sr}_2\text{CaCu}2\text{O}{8+x}$ , do not display the superfluid suppression. These observations suggest that hBN/($ \kappa$ -ET) realizes a cavity-altered superconducting ground state. This work highlights the potential of dark cavities devoid of external photons for engineering electronic ground-state properties of materials using IR-active phonons.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 4 figures
Mechanics of three-dimensional micro-architected interpenetrating phase composites
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
Andrew Y. Chen, Carlos M. Portela
Composite materials are used across engineering applications for their superior mechanical performance, a result of efficient load transfer between the structure and matrix phases. However, the inherently two-dimensional structure of laminated composites reduces their robustness to shear and out-of-plane loads, while unpredictable interlaminar failure and fiber pull-out can cause a catastrophic loss of load capacity. Meanwhile, advances toward uncovering structure-property relations in architected materials have led to highly tunable mechanical properties, deformation, and even failure. Some of these architected materials have reached near-theoretical limits; however, the majority of current work focuses on describing the response of a single-material network in air, and the effect of adding a load-bearing second phase to a three-dimensional architecture is not well understood. Here, we develop facile fabrication methods for realizing centimeter-scale polymer- and carbon-based architected interpenetrating phase composite (IPC) materials, i.e., two-phase materials consisting of a continuous 3D architecture surrounded by a load-bearing matrix across length scales, and determine the effect of geometry and constituent material properties on the mechanics of these architected IPCs. Using these experiments together with computational models, we show that the matrix phase distributes stress effectively, resulting in a high-strength, stable response. Notably, failure delocalization enhances energy dissipation of the composite, achieving specific energy absorption (SEA) values comparable to those of wound fiber tubes. Finally, we demonstrate that the stress state in an IPC can be tuned using geometric design and introduce an example in an architected composite. Altogether, this work bridges the gap between mechanically efficient composites and tunable architected materials.
Soft Condensed Matter (cond-mat.soft)
20 pages of main text, 6 figures, appendix
Emergence of Anti-chemotactic Flocking in Active Biomimetic Colloids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
Joseph D. Lopes, Benjamin Winterstrain, Fernando Caballero, Amélie Chardac, Izaiah Alvarado, Adrielle T. Cusi, Shibani Dalal, Gess Kelly, Michael R. Stehnach, Bruce L. Goode, Thomas G. Fai, Michael F. Hagan, Michael M. Norton, Guillaume Duclos
Competition for resources is a fundamental constraint that guides the self-organization of natural, biological, and human systems, ranging from urban planning and ecosystem development to intracellular pattern formation. Here, we reveal that competition for resources is at the origin of the collective dynamics that emerge in a population of colloids propelled by actin treadmilling, an out-of-equilibrium process where filaments grow from one end while shrinking from the other. Using a combination of experiments and theory, we show that symmetry-breaking, self-propulsion, and flocking emerge from the local competition for actin monomers. We demonstrate that beads propelled by actin treadmilling are anti-chemotactic and spontaneously generate asymmetric actin gradients that trigger and sustain directed motility. Flocking emerges from the combined effects of anti-chemotaxis and local competition for monomers. The flocking transition depends on the actin polymerization rate, actin monomer diffusivity, and the bead’s motility, whose interplay controls the emergence of short-range attractive interactions between the colloids. Our findings demonstrate that active stress generation coupled to reaction-diffusion is a generic mechanism that can lead to a multiscale cascade of behaviors when active agents remodel their environment. Actin treadmilling offers a platform to study how motile agents that interact through a field self-organize in novel dynamical phases, with potential applications in non-reciprocal and trainable active matter.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
15 pages and 5 figures in main text, supplementary material supplied
Cross-scale Modeling of Polymer Topology Impact on Extrudability through Molecular Dynamics and Computational Fluid Dynamics
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
Yawei Gao, Jan Michael Carrillo, Logan T. Kearney, Polyxeni P. Angelopoulou, Nihal Kanbargi, Arit Das, Michael Toomey, Bobby G. Sumpter, Joshua T. Damron, Amit K Naskar
Understanding how polymer topology influences melt extrudability is critical for advancing material design in extrusion-based additive manufacturing. In this work, we develop a bottom-up, cross-scale modeling framework that integrates coarse-grained molecular dynamics (CGMD) and continuum-scale computational fluid dynamics (CFD) to quantitatively assess the effects of polymer architecture on extrudability A range of branched polydimethylsiloxane (PDMS) polymers are systematically designed by varying backbone length, sidechain length, grafting density, grafted block ratio, and periodicity of grafted-ungrafted segments. CGMD simulations are used to compute zero-shear viscosity and relaxation times, which are then incorporated into the Phan-Thien-Tanner (PTT) model within a computational fluid dynamics (CFD) model to predict pressure drop of PDMS during extrusion through printer nozzle. Qualitative analysis reveals that polymers with concentrated grafted blocks exhibit significantly higher zero-shear viscosity than stochastically branched analogs, while sidechain inertia drives longer relaxation time. However, for untangled and weakly entangled PDMS, relaxation time remains in the nanosecond range, making shear-thinning and elastic effects negligible. Consequently, zero-shear viscosity emerges as the primary determinant of extrudability. This cross-scale modeling strategy provides a predictive framework for guiding the rational design of extrudable polymer materials with tailored topologies.
Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)
Condensate Fraction Scaling and Specific Heat Anomaly around Berezinskii-Kosterlitz-Thouless Transition of Superconductivity and Superfluidity
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-26 20:00 EDT
Characterizing the superconducting and superfluid transitions in two-dimensional (2D) many-body systems is of broad interest and remains a fundamental issue. In this study, we establish the {\it condensate fraction} as a highly effective tool to achieve that and accordingly propose efficient schemes for accurately determining the transitions, via numerically exact quantum Monte Carlo simulations. Using the 2D attractive Fermi-Hubbard model as a testbed, we access unprecedented system sizes (up to 4096 lattice sites) and perform a comprehensive analysis for the temperature dependence and finite-size scaling of {\it condensate fraction} across the Berezinskii-Kosterlitz-Thouless (BKT) transition. We demonstrate that this quantity exhibits algebraic scaling below the transition and exponential scaling above it, with significantly smaller finite-size effect comparing to the extensively studied on-site pairing correlator. This greatly improves the determination of BKT transition with moderate system sizes. We also extract the finite-size BKT transition temperature from condensate fraction, and confirm its logarithmic correction on system size. Furthermore, we find that the specific heat displays an anomaly, showing a peak at a temperature slightly above BKT transition. Our findings should be generally applicable to 2D fermionic and bosonic systems hosting superconductivity or superfluidity.
Strongly Correlated Electrons (cond-mat.str-el)
5 pages, 4 figures; Supplementary Material
Resonance-enhanced Floquet cavity electromagnonics
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-26 20:00 EDT
Amin Pishehvar, Zixin Yan, Zhaoyou Wang, Yu Jiang, Yizhong Huang, Josep M. Jornet, Liang Jiang, Xufeng Zhang
Floquet engineering has been recently recognized as an important tool for manipulating the coherent magnon-photon interaction in cavity electromagnonics systems at microwave frequencies. In spite of the novel hybrid magnonic functionalities that have been demonstrated, the effect of the Floquet drive has been relatively weak due to the limited driving efficiency, limiting its broader application. This work shows that by utilizing LC resonances, the Floquet drive in our cavity electromagnonic device can be drastically enhanced, giving rise to drastically boosted interaction between hybrid modes with fundamentally different spectral characteristics compared with previous demonstrations. In addition, the Floquet drives can also be obtained from GHz signals on such a system, allowing the demonstration of more advanced signal operations. Our novel resonance-enhanced Floquet cavity electromagnonics points to a new direction to fully unleash the potential of Floquet hybrid magnonics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 7 figures
Cubic ReSTe as a High-Performance Thermoelectric Material
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Haruka Matsumoto, Hiroto Isomura, Keita Kojima, Ryutaro Okuma, Hironori Ohshima, Chul-Ho Lee, Youichi Yamakawa, Yoshihiko Okamoto
We report thermoelectric properties of sintered samples of undoped, W-doped, and Sb-doped ReSTe crystallized in a cubic MoSBr-type structure. All samples exhibited p-type thermoelectric properties. ReSTe and Re0.993W0.007STe exhibited the largest dimensionless figure of merit ZT, reaching 0.4 at 660 K. This high performance is attributed to large power factor owing to the degenerate semiconducting state realized by the strong spin-orbit coupling and low lattice thermal conductivity of the sintered samples. Furthermore, electronic band dispersion of ReSTe is almost flat at the bottom of the conduction band, suggesting that n-type ReSTe is expected to exhibit much higher performance than p-type ReSTe.
Materials Science (cond-mat.mtrl-sci)
6 pages, 6 figures
The Discovery Engine: A Framework for AI-Driven Synthesis and Navigation of Scientific Knowledge Landscapes
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
Vladimir Baulin, Austin Cook, Daniel Friedman, Janna Lumiruusu, Andrew Pashea, Shagor Rahman, Benedikt Waldeck
The prevailing model for disseminating scientific knowledge relies on individual publications dispersed across numerous journals and archives. This legacy system is ill suited to the recent exponential proliferation of publications, contributing to insurmountable information overload, issues surrounding reproducibility and retractions. We introduce the Discovery Engine, a framework to address these challenges by transforming an array of disconnected literature into a unified, computationally tractable representation of a scientific domain. Central to our approach is the LLM-driven distillation of publications into structured “knowledge artifacts,” instances of a universal conceptual schema, complete with verifiable links to source evidence. These artifacts are then encoded into a high-dimensional Conceptual Tensor. This tensor serves as the primary, compressed representation of the synthesized field, where its labeled modes index scientific components (concepts, methods, parameters, relations) and its entries quantify their interdependencies. The Discovery Engine allows dynamic “unrolling” of this tensor into human-interpretable views, such as explicit knowledge graphs (the CNM graph) or semantic vector spaces, for targeted exploration. Crucially, AI agents operate directly on the graph using abstract mathematical and learned operations to navigate the knowledge landscape, identify non-obvious connections, pinpoint gaps, and assist researchers in generating novel knowledge artifacts (hypotheses, designs). By converting literature into a structured tensor and enabling agent-based interaction with this compact representation, the Discovery Engine offers a new paradigm for AI-augmented scientific inquiry and accelerated discovery.
Soft Condensed Matter (cond-mat.soft), Artificial Intelligence (cs.AI)
Superinsulating behavior in granular Pb film on gated few-layer MoS$_2$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-26 20:00 EDT
Suraina Gupta, Santu Prasad Jana, Pawan Kumar Gupta, Anjan K. Gupta
We report a super-insulating behavior, in a device having granular Pb film on back-gated few-layer $ \mathrm{MoS_2}$ , below an onset temperature same as the critical temperature $ T_{\rm C}\approx7$ K of bulk Pb. Below $ T_{\rm C}$ , the current-voltage characteristics exhibit a threshold voltage marking a crossover between the low-bias insulating and the high-bias normal-resistance states, consistent with the known super-insulating state behavior. A temperature dependent critical magnetic field is also found above which the insulating behavior is suppressed. The threshold voltage is found to vary with the gate-voltage but the critical field remains unchanged. With reducing temperature, the sample conductance saturates to a finite value, which depends on magnetic field and gate-voltage. This saturation behavior is found to be inconsistent with the charge-BKT and the thermal activation models but it can be fitted well to a combination of thermal activation and quantum fluctuations.
Superconductivity (cond-mat.supr-con), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
8 pages, 5 figures
Activity-enhanced shear thinning of flexible linear polar polymers
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
Arindam Panda, Roland G. Winkler, Sunil P. Singh
The rheological properties of tangentially propelled flexible polymers under linear shear flow are studied by computer simulations and are compared with analytical calculations. We find a significant impact of the coupled nonequilibrium active and shear forces on the polymer characteristics. The polar activity enhances shear-induced stretching along the flow direction, shrinkage in the transverse direction, and implies a strongly amplified shear-thinning behavior. The characteristic shear rate for the onset of these effects is determined by the activity. In the asymptotic limit of large activities, the shear-induced features become independent of activity, and for asymptotically large shear rates, shear dominates over activity with passive polymer behavior.
Soft Condensed Matter (cond-mat.soft)
11 pages, 10 figures
Physical Review E 111, 055413 (2025)
Global optimisation of the control strategy of a Brownian information Engine: Efficient information-energy exchange in a generalised potential energy surface
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
An information engine harnesses energy from a single heat bath, utilising the gathered information. This study explores the best control strategy of a Brownian information engine (BIE), confined in a potential energy surface (PES) of arbitrary shape, and experiencing a measurement outcome-based feedback cycle. The feedback site corresponds to an instantaneous shift in the potential centre to an additional feedback distance over the measurement outcome. The strategy for the most efficient information-to-energy conversion is achieved when the position of the global potential minimum corresponds to the additional feedback distance. The BIE acts as a heater if and only if the average potential energy is higher than the energy at the additional feedback distance. Operating under confinement PES of different shapes, the BIE can harness energy beyond the average potential energy, and multiple heater-refrigerator re-entrance events are feasible. The consequences of the best control strategy are explained using sufficient examples.
Soft Condensed Matter (cond-mat.soft)
12 pages and 8 figures
Multi-shot readout error benchmark of the nitrogen-vacancy center’s electronic qubit
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-26 20:00 EDT
Péter Boross, Domonkos Svastits, Győző Egri, András Pályi
The ground-state electronic spin of a negatively charged nitrogen-vacancy center in diamond can be used for room-temperature experiments showing coherent qubit functionality. At room temperature, photoluminescence-based qubit readout has a low single-shot fidelity; however, the populations of the qubit’s two basis states can be inferred using multi-shot readout. In this work, we calculate the dependence of the error of a multi-shot inference method on various parameters of the readout process. This multi-shot readout error scales as $ \Delta/\sqrt{N}$ , with $ N$ being the number of shots, suggesting to use the coefficient $ \Delta$ as a simple multi-shot readout error benchmark. Our calculation takes into account background photons, photon loss, and initialization error. Our model enables the identification of the readout error budget, i.e., the role various imperfections play in setting the readout error. Our results enable experimentalists and engineers to focus their efforts on those hardware improvements that yield the highest performance gain for multi-shot readout.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
12 pages, 4 figues
Improved imaging of magnetic domains with a photoelectron emission microscope by utilizing symmetry and momentum selection
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
F. O. Schumann, M. Paleschke, J. Henk, W. Widdra, C.-T. Chiang
Imaging of magnetic domains with a photoelectron emission microscope operated with photon energies in the threshold regime often suffers from low contrast. In this work we show by symmetry considerations, photoemission calculations, and imaging experiments, how the contrast can be improved significantly. The key to both domain selectivity and sizable intensity asymmetries is, guided by symmetry considerations, selecting the momenta of the photoelectrons by a properly positioned contrast aperture. By comparing computational with experimental results for an Fe(001) surface we prove the feasibility of the approach.
Materials Science (cond-mat.mtrl-sci)
Universal momentum tail of identical one-dimensional anyons with two-body interactions
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-05-26 20:00 EDT
Raúl Hidalgo-Sacoto, Thomas Busch, D. Blume
Non-relativistic anyons in 1D possess generalized exchange statistics in which the exchange of two identical anyons generates a non-local phase that is governed by the spatial ordering of the particles and the statistical parameter $ \alpha$ . Working in the continuum, we demonstrate the existence of two distinct types of 1D anyons, namely bosonic anyons and fermionic anyons. We identify a many-body Hamiltonian with additive two-body zero-range interactions that supports bosonic and fermionic anyon eigenstates, which are, for arbitrary interaction strength, related through a generalized bosonic-anyon–fermionic-anyon mapping, an extension of the celebrated Bose-Fermi mapping for zero-range interacting 1D systems. The momentum distributions of bosonic and fermionic anyons are distinct: while both feature $ k^{-2}$ and $ k^{-3}$ tails, the associated prefactors differ. Our work reveals intricate connections between the generalized exchange statistics, the universal two- and three-body Tan contacts of systems consisting of $ N$ identical particles, and the emergence of statistics-induced chiral symmetry breaking.
Quantum Gases (cond-mat.quant-gas)
15 pages, 2 figures
Patterns with long and short-range order in monoloyers of binary mixtures with competing interactions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
M. Litniewski, W. T. Gozdz nd A. Ciach
Lateral microsegregation in a monolayer of a binary mixture of particles or macromolecules is studied by MD simulations in a generic model with the interacting potentials inspired by effective interactions in biological or soft-matter systems. In the model, the energy is minimized when like particles form small clusters, and the cross-interction is of opposite sign.
We show that the laterally microsegregated components in the dense ordered phases form alternating stripes for similar densities, or the clusters of the minority component fill the hexagonally distributed voids formed in the dense phase of the majority component. A qualitative phase diagram in the plane of densities of the two components is constructed for low temperatures. An addition of the second component significantly enlarges the temperature range of the stability of the ordered phases compared to the stability of these phases in the one-component system. At higher temperatures, the disordered phase consisting of individual particles, one-component clusters and two-component super-clusters of various sizes is stable. The product kn(k), with n(k) denoting the average number of super-clusters composed of k particles, decays exponentially with k, and the inverse decay rate depends linearly on temperature.
Soft Condensed Matter (cond-mat.soft)
Contribution of shears on vibrational entropy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Calculating the vibrational entropy of an N-atom assembly in the harmonic approximation requires the diagonalisation of a large matrix. This operation becomes rapidly time consuming when increasing the dimensions of the simulation cell. In the studies of point defects, a widely used shortcut consists in calculating the eigen modes of the atoms contained in an inner region, called the defective region, while the atoms belonging to the outer region are held fixed, and in applying an elastic correction to account for the entropy stored in the distortion of the outer region. A recent paper proposed to base the correction on the local pressure change experienced by each lattice site. The present contribution is an extension in the sense that it includes the shears. We compared the two approximations for configurations which are currently encountered in defect studies, namely those pertaining to defect formation and migration. The studied defects are the single, di- and tri-vacancy as well as the dumbbell interstitial in a host matrix modelled by several empirical potentials mimicking pure copper. It is shown that the inclusion of shears brings a noticeable contribution to the elastic correction for all configurations of low symmetry.
Materials Science (cond-mat.mtrl-sci)
48 pages ; 8 tables ; 5 figures
Philosophical Magazine 2007 Vol.87 (issue 22); p. 3259-3295
Anatomy of spin-orbit-torque-assisted magnetization dynamics in Co/Pt bilayers: Importance of the orbital torque
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Harshita Devda, András Deák, Leandro Salemi, Levente Rózsa, László Szunyogh, Peter M. Oppeneer, Ulrich Nowak
Understanding the mechanism driving magnetization switching in spin-orbit-torque-assisted devices remains a subject of debate. While originally attributed to the spin Hall effect and spin Rashba-Edelstein effect, recent discoveries related to orbital moments induced by the orbital Hall effect and the orbital Rashba-Edelstein effect have added complexity to the comprehension of the switching process in non-magnet/ferromagnet bilayers. Addressing this challenge, we present a quantitative investigation of a Pt/Co bilayer by employing atomistic spin dynamics simulations, incorporating the proximity-induced moments of Pt, as well as electrically induced spin and orbital moments obtained from first-principles calculations. Our layer-resolved model elucidates the damping-like and field-like nature of the induced moments by separating them according to their even and odd magnetization dependence. In addition to demonstrating that a larger field-like spin-orbit torque contribution comes from previously disregarded induced orbital moments, our work highlights the necessity of considering interactions with Pt induced moments at the interface, as they contribute significantly to the switching dynamics.
Materials Science (cond-mat.mtrl-sci)
Star-like thermoresponsive microgels: a new class of soft nanocolloids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
Elisa Ballin, Francesco Brasili, Tommaso Papetti, Jacopo Vialetto, Michael Sztucki, Simona Sennato, Marco Laurati, Emanuela Zaccarelli
We provide experimental and numerical evidence of a new class of soft nanocolloids: star-like microgels with thermoresponsive character. This is achieved by using the standard precipitation polymerization synthesis of poly(N-isopropylacrylamide) (PNIPAM) microgels and replacing the usually employed crosslinking agent, N,N’-methylenebis(acrylamide) (BIS), with ethylene glycol dimethacrylate (EGDMA). The fast reactivity of EGDMA combined with its strong tendency to self-bind produces colloidal networks with a central, crosslinker-rich core, surrounded by a corona of long, crosslinker-free arms. These novel star-like microgels fully retain PNIPAM thermoresponsivity and undergo a volume phase transition at a temperature of 32°C that is very sharp as compared to standard PNIPAM-BIS microgels, independently of crosslinker content. Dynamic light scattering and small angle X-ray scattering experiments are compared to extensive simulation results, based on ideal star polymers as well as on state-of-the-art monomer-resolved simulations, offering a microscopic evidence of the star-like internal structure of PNIPAM-EGDMA microgels. This can be described by a novel model for the form factors combining star and microgel features. The present work thus bridges the fields of star polymers and microgels, providing the former with the ability to respond to temperature via a facile synthetic route that can be routinely employed, opening the way to exploit these soft particles for a variety of fundamental studies and applicative purposes.
Soft Condensed Matter (cond-mat.soft)
Near-Unity Charge Readout in a Nonlinear Resonator without Matching
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-26 20:00 EDT
Harald Havir, Andrea Cicovic, Pierre Glidic, Subhomoy Haldar, Sebastian Lehmann, Kimberly A. Dick, Ville F. Maisi
In this paper, we present a nonlinear resonator performing the readout of a charge-sensing quantum dot. We show that by driving the resonator in the nonlinear regime, we achieve a near-unity signal. This despite not satisfying the impedance matching requirements necessary for such large signals in the linear regime. Our experiments, supported by numerical calculations, demonstrate that the signal increase stems from the sensor dissipation shifting the onset of the nonlinear resonator response. By lifting the matching requirement, we increase the bandwidth limit of resonator readout-based charge detection by an order of magnitude, opening up the avenue to ultra-fast charge detectors.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con), Instrumentation and Detectors (physics.ins-det)
10 pages, 5 figures
Inverse thermal anisotropy in CdMgO measured using photothermal infrared radiometry and thermoreflectance
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Misha Khalid, Ankur Chatterjee, Ewa Przezdziecka, Abinash Adhikari, Monika Stanke, Aleksandra Wierzbicka, Carlos J. Tavares, Michał Pawlak
This study elucidates the intriguing phenomenon of inverse thermal anisotropy in cadmium magnesium oxide (CdMgO) thin films, characterized by cross-plane thermal conductivity being greater than in-plane thermal conductivity, essential for optimizing thermal management in next-generation optoelectronic devices. Herein, we utilized Photothermal Radiometry and Frequency Domain Thermoreflectance to precisely determine the thermal conductivity and diffusivity across various concentrations of magnesium in CdMgO alloys, thereby providing essential insights into thermophysical behavior. Atomic force microscopy and X-ray diffraction revealed a direct correlation between increasing magnesium content and progressive structural evolution within plasma-assisted molecular beam epitaxy-derived CdMgO alloys. Furthermore, heat transport mechanism, analyzed using Callaway and Abeles models, indicated key phonon interactions. This comprehensive investigation provides a framework for the precise control of CdMgO thin film thermal properties, paving the way for scalable fabrication strategies to optimize performance in high-power thermal management applications.
Materials Science (cond-mat.mtrl-sci)
Polarization Vortices in a Ferromagnetic Metal via Twistronics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Yingzhuo Lun, Xinxin Hu, Qi Ren, Umair Saeed, Kapil Gupta, Bernat Mundet, Ivan Pinto-Huguet, Jose Santiso, Jessica Padilla-Pantoja, Jose Manuel Caicedo Roque, Yunpeng Ma, Qian Li, Gang Tang, David Pesquera, Xueyun Wang, Jiawang Hong, Jordi Arbiol, Gustau Catalan
Recent advances in moire engineering provide new pathways for manipulating lattice distortions and electronic properties in low-dimensional materials. Here, we demonstrate that twisted stacking can induce dipolar vortices in metallic SrRuO3 membranes, despite the presence of free charges that would normally screen depolarizing fields and dipole-dipole interactions. These polarization vortices are correlated with moire-periodic flexoelectricity induced by shear strain gradients, and exhibit a pronounced dependence on the twist angle. In addition, multiferroic behavior emerges below the ferromagnetic Curie temperature of the films, whereby polarization and ferromagnetism coexist and compete, showing opposite twist-angle dependencies of their respective magnitudes. Density functional theory calculations provide insights into the microscopic origin of these observations. Our findings extend the scope of polarization topology design beyond dielectric materials and into metals.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Manuscript(14 pages, 4 figures)+Supplementary Information
Symmetry breaking and thermal phase transition of the spin-1 quantum magnet with SU(3) symmetry on the simple cubic lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-26 20:00 EDT
Nils Caci, Dominik Chudy, Pablo Daniel Mendez Mariscal, Daniel Ueltschi, Stefan Wessel
Using a combined analysis from Poisson-Dirichlet and symmetry-breaking calculations as well as quantum Monte Carlo simulations, we examine the ordered phase and the thermal phase transition of the three-dimensional spin-1 quantum magnet on the simple cubic lattice with bilinear and biquadratic interactions and SU(3) internal symmetry. We obtain exact results for the order parameter distribution function that compare well to the quantum Monte Carlo data. Furthermore, based on a detailed finite-size analysis, we provide evidence that the thermal melting transition at the SU(3) point is either weakly first-order in this system or, if continuous, it falls beyond the unitary-bounds of conformal field theory.
Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 9 figures
Efficient method for magnetic structure exploration based on first-principles calculations: application to MnO and hexagonal ferrites SrFe${12}$O${19}$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Taro Fukazawa, Haruki Okumura, Tetsuya Fukushima, Hisazumi Akai, Takashi Miyake
We propose an approach for exploring magnetic structures by using Liechtenstein’s method for exchange couplings from the results of first-principles calculations. Our method enables efficient and accurate exploration of stable magnetic structures by greatly reducing the number of firstprinciples calculations required. We apply our method to the magnetic structures of MnO and hexagonal ferrite SrFe12O19. Our method correctly identifies the ground-state magnetic structure with a small number of first-principles calculations in these systems.
Materials Science (cond-mat.mtrl-sci)
13 pages, 7 figures
Fine-tuning the dispersion of active suspensions with oscillatory flows
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
Hakan Osman Caldag, Martin Alan Bees
The combined impact of axial stretching and cross-stream diffusion on the downstream transport of solute is termed Taylor dispersion. The dispersion of active suspensions is qualitatively distinct: viscous and external torques can establish non-uniform concentration fields with weighted access to shear, modifying mean drift and effective diffusivity. It would be advantageous to fine-tune the dispersion for systems such as bioreactors, where mixing or particle separation can improve efficacy. Here, we investigate the dispersion of active suspensions in a vertical channel driven by an oscillatory pressure gradient - Womersley flow - using gyrotactic swimmers (bottom-heavy cells subject to viscous torques). Preliminary experimental results reveal interesting dispersion phenomena, highly dependent on the oscillation parameters, motivating theoretical investigation. Employing Lagrangian simulations, we find that oscillatory flows can induce drift and increase lateral and downstream dispersion, with periodic mixing between left and right sides. Such flows can also be used to separate species with different motile behaviour. Eulerian numerical schemes typically require an approach to averaging in orientational space, such as generalised Taylor dispersion, with assumptions on translational and rotational time scales. For an oscillatory timescale commensurate with cell dynamics, we reveal the limitations of such approximations, beyond which the averaging techniques collapse.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Fluid Dynamics (physics.flu-dyn)
16 pages, 5 figures, 2 tables
Light-Driven Bound State of Interacting Impurities in a Dirac-Like Bath
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-26 20:00 EDT
Recent investigations have revealed the presence of exceptional points in the low-energy effective spin-interacting impurity model, previously explored via non-Hermitian renormalization group (RG) techniques. These studies uncovered novel RG fixed points and linked them to distinct transport signatures. In this work, we revisit the model from a real-time field-theoretic perspective, studying both non-interacting and strongly correlated ($ U = \infty$ ) limits using the exact equation of motion and a Large-$ N$ Keldysh variational mean-field approach. Remarkably, we find that the steady-state solutions of the Keldysh action exhibit the same fixed point structure as the RG flows, independently recovering the exceptional behavior. Our analysis further reveals that exceptional points (EPs) arise naturally in the Green’s function structure without any ad hoc non-Hermitian terms and are associated with self-consistent light-induced hybridization in specific regimes. Importantly, we identify a new causal steady state in which the appearance of EPs is not inherently tied to causality violation; instead, a sign-reversing (negative) flip hybridization contribution restores causality. These findings suggest a broader framework in which EPs coexist with well-defined dynamical behavior and open the door to controlled light-driven engineering of dissipative quantum impurity states.
Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 7 figures
The bridge function as a functional of the radial distribution function: Operator learning and application
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-26 20:00 EDT
Martin Panholzer, Michael Haring, Thomas Wallek, Robert E. Zillich
Properties of classical molecular systems can be calculated with integral equation theories based on the Ornstein-Zernike (OZ) equation and a complementing closure relation. One such closure relation is the hyper netted chain (HNC) approximation, which neglects the so-called bridge function. We present a new way to use machine learning to train a deep operator network to predict the bridge function, based on the radial distribution function as input. Bridge functions for the Lennard-Jones fluid are calculated from Monte Carlo simulations in a wide range of densities and temperatures. These results are used to train the deep operator network. This network is employed to improve the HNC closure by the prediction for the bridge function, and the resulting set of equations is solved iteratively. For assessment, we compare the radial distribution function and the pressure, calculated by the viral expression, with Monte Carlo results and standard HNC. We demonstrate that incorporating the neural network based bridge function in the closure relation leads to substantially improved predictions. Universality of our method is demonstrated by comparing results for the hard sphere fluid, calculated with our model trained on the Lennard-Jones fluid, with exact hard sphere results, showing overall good agreement.
Statistical Mechanics (cond-mat.stat-mech)
10 pages, 7 figures, 1 table
Relationship of structural disorder and stability of supercooled liquid state with glass-forming ability of metallic glasses
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-05-26 20:00 EDT
J.B. Cui, R.A. Konchakov, G.V. Afonin, A.S. Makarov, G.J. Lyu, J.C.Qiao, N.P. Kobelev, V.A. Khonik
We performed calorimetric studies of 26 metallic glasses and calculated the excess entropy and excess enthalpy with respect to their counterpart crystals. On this basis, we introduced a dimensionless entropy-based parameter {\sigma}scl, which characterizes structural disordering and stability of the supercooled liquid state upon heating. A very good correlation of {\sigma}scl with literature data on the critical cooling rate Rc and critical diameter Dmax of metallic glasses is shown. We also introduced another dimensionless parameter {\eta}scl based on the excess enthalpy of glass and showed that {\eta}scl provides equally good correlation with Rc and Dmax. Possible relationship of structural disordering and glass-forming ability in the supercooled liquid range with the defect structure of glass is discussed. The obtained results provide a new window for the understandingof the glass-forming ability of metallic glasses.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
14 ages, 4 figures
Subsystem localization
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-26 20:00 EDT
Arpita Goswami, Pallabi Chatterjee, Ranjan Modak, Shaon Sahoo
We consider a ladder system where one leg, referred to as the bath", is governed by an Aubry-André (AA) type Hamiltonian, while the other leg, termed the subsystem”, follows a standard tight-binding Hamiltonian. We investigate the localization properties in the subsystem induced by its coupling to the bath. For the coupling strength larger than a critical value ($ t’>t’_c$ ), the analysis of the static properties show that there are three distinct phases as the AA potential strength $ V$ is varied: a fully delocalized phase at low $ V$ , a localized phase at intermediate $ V$ , and a weakly delocalized (fractal) phase at large $ V$ . An analysis of the wavepacket dynamics shows that the delocalized phase exhibits a ballistic behavior, whereas the weakly delocalized phase is subdiffusive. Interestingly, we also find a superdiffusive narrow crossover regime along the line separating the delocalized and localized phases. When $ t’<t’_c$ , the intermediate localized phase disappears, and we find a delocalized (ballistic) phase at low $ V$ and a weakly delocalized (subdiffusive) phase at large $ V$ . Between those two phases, there is also a crossover regime where the system can be super- or subdiffusive. Finally, in some limiting scenario, we also establish a mapping between our ladder system and a well-studied one-dimensional generalized Aubry-André (GAA) model.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
12 pages, 17 figures
Anisotropic spin-polarized conductivity in collinear altermagnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Mingbo Dou, Xianjie Wang, L. L. Tao
The altermagnet exhibits the nonrelativistic spin splitting that enables all-electrical generation of spin-polarized currents beyond the spin-orbit coupling. Here, we report on a study on the anisotropic spin-polarized conductivity in collinear altermagnets. Based on the Boltzmann transport theory, we first study this effect using the general group-theoretical analysis and identify the spin point groups sustaining the finite spin polarization defined in terms of spin-polarized conductivity. We show that the spin polarization vanishes along any direction for the $ g$ -wave and $ i$ -wave altermagnets while the spin polarization is significantly anisotropic for the $ d$ -wave altermagnet. We further derive the analytical expressions for the anisotropic spin polarization in the $ d$ -wave altermagnets. Then, we exemplify those phenomena in several representative altermagnets based on the density functional theory calculations. Our work enriches the altermagnetic spintronics and paves the practical way to produce large spin polarization in collinear altermagnets.
Materials Science (cond-mat.mtrl-sci)
Non-isothermal stress relaxation in conventional and high-entropy metallic glasses and its relationship to themixing and excess entropy
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-05-26 20:00 EDT
G.V. Afonin, S.L. Scherbakov, R.A. Konchakov, N.P. Kobelev, J.B. Cui, J.C. Qiao, V.A. Khonik
We performed calorimetric and torsion stress relaxation measurements upon linear heating of six conventional and high-entropy metallic glasses with the mixing entropy {\Delta}Smix ranging from 0.86R to 1.79R (R is the universal gas constant). It is shown that high-entropy metallic glasses ({\Delta}Smix > 1.5 R) exhibit significantly greater resistance to stress relaxation. Based on calorimetric data, we calculated the excess entropy of glass relative to the counterpart crystalline state and introduced an entropy-based dimensionless parameter {\Delta}S, which characterizes the rise of the entropy and structural disordering of glass in the supercooled liquid region. It is shown that the depth of stress relaxation at a given temperature decreases with {\Delta}Smix but increases with {\Delta}S. Possible reasons for this relationship are discussed.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
15 pages, 5 figures
In-plane polarization induced ferroelectrovalley coupling in a two-dimensional rare-earth halide
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
We propose a mechanism where the valley splitting is caused by an in-plane electric polarization and the coupling between the two makes it possible for an electric field to control the valley degree of freedom. We demonstrate this by considering Gd-substituted EuCl$ _2$ monolayer in its 1T-phase using first-principles calculations. This monolayer exhibits an in-plane polarization which breaks the inversion symmetry of the monolayer leading to a spontaneous valley splitting. The resulting valley polarization is strongly coupled with the electric polarization and, hence, the valley degree of freedom can be switched by an external electric field in this case, instead of the conventional magnetic field. We show that a similar ferroelectric-ferrovalley (FE-FV) coupling can also exist in the previously reported ferroelectric (CrBr$ _3$ )$ _2$ Li monolayer. This mechanism opens up a new avenue for electric field control of valley polarization in two-dimensional materials.
Materials Science (cond-mat.mtrl-sci)
7 pages, 5 figures
Tunability of the magnetic properties in Ni intercalated transition metal dichalcogenide NbSe$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Xujia Gong, Amar Fakhredine, Carmine Autieri
Ni$ _{0.33}$ NbSe$ _2$ has been identified as an altermagnet with a Neel temperature of 84 K, although Ni$ _{0.21}$ NbSe$ _2$ behaves like a nonmagnetic metal. In this work, we explore the magnetic phases of Ni-intercalated NbSe$ _2$ with stoichiometry Ni$ _{0.25}$ NbSe$ _2$ , which lies between the two previously studied compositions. Our results reveal a transition in the ground state from a stripe antiferromagnetic phase with Kramers degeneracy to a ferromagnetic phase (above UC).In the Kramers antiferromagnetic state, the nearest-neighbour magnetic coupling is ferromagnetic between the layers and forms stripe-like patterns in the ab plane. This behavior contrasts with that of Ni$ _{0.33}$ NbSe$ _2$ where the nearest-neighbour magnetic couplings are opposite, and the magnetic easy axis aligns along the z-axis. The strong magnetocrystalline anisotropy and the second-nearest neighbor coupling stabilize the Kramers antiferromagnetic and ferromagnetic phases with spins aligned along the z-axis over the non-collinear 120 phase with in-plane spin orientations. Given the triangular lattice and the closeness to both ferromagnetic and antiferromagnetic coupling, a metamagnetic transition is possible. Substantial modifications to the electronic structure accompany Ni intercalation in NbSe$ _2$ with respect to the pristine phase. Compared to pristine NbSe$ _2$ , which features a hole pocket at the $ \Gamma$ point, the stripe phase of Ni$ _{0.25}$ NbSe$ _2$ instead exhibits an electron pocket at $ \Gamma$ . This pocket at $ \Gamma$ has predominantly 3z$ ^2$ -r$ ^2$ character, and derives its main spectral weight from the Nb atoms. Ni intercalation also shifts the Van Hove singularity away from the Fermi level, thereby suppressing potential electronic instabilities.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
11 pages, 10 figures
Majorana vortex phases in time-reversal invariant higher-order topological insulators and topologically trivial insulators
New Submission | Superconductivity (cond-mat.supr-con) | 2025-05-26 20:00 EDT
Majorana vortex phases have been extensively studied in topological materials with conventional superconducting pairing. Inspired by recent experimental progress in realizing time-reversal invariant higher-order topological insulators (THOTIs) and inducing superconducting proximity effects, we investigate Majorana vortex phases in these systems. We construct THOTIs as two copies of a topological insulator (TI) with time-reversal symmetry-preserving mass terms that anisotropically gap the surface states. We find that these mass terms have a negligible impact on the vortex phase transitions of double TIs when treated as perturbations, and no additional topological phase transitions are induced. Consequently, $ \mathbb{Z}_2$ -protected Majorana vortex end modes (MVEMs) emerge when the chemical potential lies between the critical chemical potentials $ \mu_c^{(1)}$ and $ \mu_c^{(2)}$ of the two TI vortex phase transitions. We demonstrate this behavior across multiple THOTI models, including rotational symmetry-protected THOTI, inversion symmetry-protected THOTI, rotational and inversion symmetries-protected THOTI bismuth, and extrinsic THOTI. Remarkably, MVEMs persist even when all surfaces are gapped with the same sign, rendering the system topologically trivial in both first- and second-order classifications. Our findings establish that MVEMs can be realized in time-reversal invariant systems with fully gapped surfaces, encompassing both topologically nontrivial and trivial insulators, thus significantly broadening the solid state material platforms for hosting Majorana vortex phases.
Superconductivity (cond-mat.supr-con)
13 pages, 5 figures
Efficient local atomic cluster expansion for BaTiO$_3$ close to equilibrium
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Anna Grünebohm, Matous Mrovec, Maxim N. Popov, Lan-Tien Hsu, Yury Lysogorskiy, Anton Bochkarev, Ralf Drautz
Barium titanate (BTO) is a representative perovskite oxide that undergoes three first-order ferroelectric phase transitions related to exceptional functional properties. In this work, we develop two atomic cluster expansion (ACE) models for BTO to reproduce fundamental properties of bulk as well as defective BTO phases. The two ACE models do not target full transferability but rather aim to examine the influence of implicit and explicit treatment of long-range Coulomb interactions. We demonstrate that both models describe equally well the temperature induced phase transitions as well as polarization switching due to applied electric field. Even though the parametrizations are based on a limited number of configurations that are mostly not far away from the equilibrium, the ACE models are able to capture also properties of important crystal defects, such as oxygen vacancies, stacking faults and domain walls. A systematic comparison shows that the phase transitions as well as the fundamental properties of the investigated defects can be described with similar accuracy with or without explicit treatment of charges and Coulomb interactions allowing for efficient short-range machine learning potentials.
Materials Science (cond-mat.mtrl-sci)
main paper: 13 pages, 10 figures, supplement: 6 pages 5 pages
Liouvillian skin effects in two-dimensional electron systems at finite temperatures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-26 20:00 EDT
Yuta Shigedomi, Tsuneya Yoshida
Liouvillian skin effects, manifested as the localization of Liouvillian eigenstates around the boundary, are distinctive features of non-Hermitian systems and are particularly notable for their impact on system dynamics. Despite their significance, Liouvillian skin effects have not been sufficiently explored in electron systems. In this work, we demonstrate that a two-dimensional electron system on a substrate exhibits $ \mathbb{Z}$ and $ \mathbb{Z}_2$ Liouvillian skin effects due to the interplay among energy dissipations, spin-orbit coupling, and a transverse magnetic field. In addition, our analysis of the temperature dependence reveals that these Liouvillian skin effects become pronounced below the energy scale of band splitting induced by the spin-orbit coupling and the magnetic field. While our Liouvillian skin effect leads to charge accumulation under quench dynamics, its relaxation time is independent of the system size, in contrast to that of previously reported Liouvillian skin effects. This difference is attributed to the scale-free behavior of the localization length, which is analogous to non-Hermitian critical skin effects.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
16 pages, 8 figures, 1 table
Pressure tuning of competing interactions on a honeycomb lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-26 20:00 EDT
Piyush Sakrikar, Bin Shen, Eduardo H. T. Poldi, Faranak Bahrami, Xiaodong Hu, Eric M. Kenney, Qiaochu Wang, Kyle W. Fruhling, Chennan Wang, Ritu Gupta, Rustem Khasanov, Hubertus Luetkens, Stuart A. Calder, Adam A. Aczel, Gilberto Fabbris, Russell J. Hemley, Kemp W. Plumb, Ying Ran, Philipp Gegenwart, Alexander A. Tsirlin, Daniel Haskel, Michael J. Graf, Fazel Tafti
Magnetic exchange interactions are mediated via orbital overlaps across chemical bonds. Thus, modifying the bond angles by physical pressure or strain can tune the relative strength of competing interactions. Here we present a remarkable case of such tuning between the Heisenberg (J) and Kitaev (K) exchange, which respectively establish magnetically ordered and spin liquid phases on a honeycomb lattice. We observe a rapid suppression of the Neel temperature (TN) with pressure in Ag3LiRh2O6, a spin-1/2 honeycomb lattice with both J and K couplings. Using a combined analysis of x-ray data and first-principles calculations, we find that pressure modifies the bond angles in a way that increases the |K/J| ratio and thereby suppresses TN. Consistent with this picture, we observe a spontaneous onset of muon spin relaxation (muSR) oscillations below TN at low pressure, whereas in the high-pressure phase, oscillations appear only when T < TN/2. Unlike other candidate Kitaev materials, Ag3LiRh2O6 is tuned toward a quantum critical point by pressure while avoiding a structural dimerization in the relevant pressure range.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
1 pdf, 3 figures, 1 table, published
Nature Communications 16, 4712 (2025)
Emergent reactance induced by the deformation of a current-driven skyrmion lattice
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Matthew T. Littlehales, Max T. Birch, Akiko Kikkawa, Yasujiro Taguchi, Diego Alba Venero, Peter D. Hatton, Naoto Nagaosa, Yoshinori Tokura, Tomoyuki Yokouchi
The interaction between conduction electrons and spin textures gives rise to remarkable phenomena associated with the Berry phase. The Berry phase acquired by conduction electrons acts as an emergent electromagnetic field, facilitating phenomena analogous to classical electromagnetism, such as the Lorentz force and electromagnetic induction. Magnetic skyrmions, spin vortices with non-trivial topology, serve as a key platform for such studies. For example, non-trivial transport responses are recognized as being induced by the emergent Lorentz force and the emergent electromagnetic induction. Despite remarkable progress in skyrmion physics, emergent reactance, in which the phase of an applied AC current is modified by emergent electromagnetism, has not been thoroughly investigated. Here, we report emergent reactance in the prototypical skyrmion-hosting material, MnSi. We observe longitudinal and Hall reactance signals as the skyrmion lattice undergoes creep motion, in which the skyrmions deform while moving. The Hall reactance is attributed to the emergent electric field associated with the inertial translational motion arising from the skyrmion effective mass. In contrast, the longitudinal reactance results from the emergent electric fields generated by the phason and spin-tilting modes excited by their deformation. Our findings shed light on the internal deformation degrees of freedom in skyrmions as a important factor for efficient generation of the emergent electric field.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Plasmon-Driven Giant Amplification of Ultrashort Spin Current
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-05-26 20:00 EDT
A key challenge in spintronics is to efficiently generate and manipulate spin current for information processing. Here we study ultrashort spin transport and associated terahertz (THz) emission in a hybrid structure comprising gold nanoparticles, a ferromagnet (FM) and a normal metal (NM) and show that plasmon excitation in the nanoparticles strongly enhances the electron-magnon scattering rate through heating effects, thereby amplifying the spin current generation at the FM$ |$ NM interface. This effect is even more pronounced when the FM is an insulator with a thickness much smaller than the nanoparticle size. In this case, the gold nanoparticle and NM substrate form a nanocavity with the FM as a dielectric layer, trapping plasmons inside the gap. The resulting spin current can be amplified by two orders of magnitude as compared to the case without plasmon excitations. Our findings provide a novel route to design efficient spintronic THz devices and further open the door to the interdisciplinary field of spintronics and nanophotonics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
6 pages, 3 figures
Dilute Paramagnetism and Non-Trivial Topology in Quasicrystal Approximant Fe$4$Al${13}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-26 20:00 EDT
Keenan E. Avers, Jarryd A. Horn, Ram Kumar, Shanta R. Saha, Yuanfeng Xu, B. Andrei Bernevig, Peter Zavalij, Johnpierre Paglione
A very fundamental property of both weakly and strongly interacting materials is the nature of its magnetic response. In this work we detail the growth of crystals of the quasicrystal approximant Fe$ _4$ Al$ _{13}$ with an Al flux solvent method. We characterize our samples using electrical transport and heat capacity, yielding results consistent with a simple non-magnetic metal. However, magnetization measurements portray an extremely unusual response for a dilute paramagnet and do not exhibit the characteristic Curie-Weiss behavior expected for a weakly interacting material at high temperature. Electronic structure calculations confirm metallic behavior, but also indicate that each isolated band near the Fermi energy hosts non-trivial topologies including strong, weak and nodal components, with resultant topological surface states distinguishable from bulk states on the (001) surface. With half-filled flat bands apparent in the calculation but absence of long-range magnetic order, the unusual paramagnetic response suggests the dilute paramagnetic behavior in this quasicrystal approximant is surprising and may serve as a test of the fundamental assumptions that are taken for granted for the magnetic response of weakly interacting systems.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
7 pages, 5 figures
Crystals 2025, 15, 485
Preferential attachment and power-law degree distributions in heterogeneous multilayer hypergraphs
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-05-26 20:00 EDT
Francesco Di Lauro, Luca Ferretti
We include complex connectivity structures and heterogeneity in models of multilayer networks or multilayer hypergraphs growing by preferential attachment. We consider the most generic connectivity structure, where the probability of acquiring a new hyperlink depends linearly on the vector of hyperdegrees of the node across all layers, as well as on the layer of the new hyperlink and the features of both linked nodes. We derive the consistency conditions that imply a power-law hyperdegree distribution for each class of nodes within each layer and of any order. For generic connectivity structures, we predict that the exponent of the power-law distribution is universal for all layers and all orders of hyperlinks, and it depends exclusively on the type of node.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Statistical Mechanics (cond-mat.stat-mech)
7 pages
Recovering Hidden Degrees of Freedom Using Gaussian Processes
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
Georg Diez, Nele Dethloff, Gerhard Stock
Dimensionality reduction represents a crucial step in extracting meaningful insights from Molecular Dynamics (MD) simulations. Conventional approaches, including linear methods such as principal component analysis as well as various autoencoder architectures, typically operate under the assumption of independent and identically distributed data, disregarding the sequential nature of MD simulations. Here, we introduce a physics-informed representation learning framework that leverages Gaussian Processes combined with variational autoencoders to exploit the temporal dependencies inherent in MD data. Time-dependent kernel functions–such as the Matérn kernel–directly impose impose the temporal correlation structure of the input coordinates onto a low-dimensional space, preserving Markovianity in the reduced representation while faithfully capturing the essential dynamics. Using a three-dimensional toy model, we demonstrate that this approach can successfully identify and separate dynamically distinct states that are geometrically indistinguishable due to hidden degrees of freedom. The resulting embedding features enhance metastability, facilitating the construction of Markov state models with smaller lag times and better convergence of implied timescales. This time-aware perspective provides a promising framework for understanding complex biomolecular systems, in which conventional collective variables may fail to capture the full dynamical picture.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph), Computational Physics (physics.comp-ph), Data Analysis, Statistics and Probability (physics.data-an)
Explaining the extra crystal field mode in ACeX2
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-26 20:00 EDT
Allen O. Scheie, Sabrina J. Li, Stephen D. Wilson, Daniel A. Rehn
A growing list of Ce-based magnets have shown an extra and heretofore unexplained crystal electric field (CEF) mode at high energies. We describe a process whereby an optical phonon can produce a split CEF mode well above the phonon energy. We use density functional theory and point-charge model calculations to estimate the phonon distortions and coupling to model this effect in KCeO$ _2$ , showing that it accounts for the extra CEF mode observed. This mechanism is generic, and may explain the extra modes observed on a variety of Ce$ ^{3+}$ compounds.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
5 pages, 7 figures
Ballistic macroscopic fluctuation theory via mapping to point particles
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-26 20:00 EDT
Jitendra Kethepalli, Andrew Urilyon, Tridib Sadhu, Jacopo De Nardis
Ballistic Macroscopic Fluctuation Theory (BMFT) captures the evolution of fluctuations and correlations in systems where transport is strictly ballistic. We show that, for \emph{generic integrable models}, BMFT can be constructed through a direct mapping onto ensembles of classical or quantum point particles. This mapping generalises the well-known correspondence between hard spheres and point particles: the two-body \emph{scattering shift} now plays the role of an effective rod length for arbitrary interactions. Within this framework, we re-derive both the full-counting statistics and the long-range correlation functions previously obtained by other means, thereby providing a unified derivation. Our results corroborate the general picture that all late-time fluctuations and correlations stem from the initial noise, subsequently convected by Euler-scale hydrodynamics.
Statistical Mechanics (cond-mat.stat-mech)
33 pages, 4 figures
Rotational Multi-material 3D Printing of Soft Robotic Matter with Asymmetrical Embedded Pneumatics
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-05-26 20:00 EDT
Jackson K. Wilt, Natalie M. Larson, Jennifer A. Lewis
The rapid design and fabrication of soft robotic matter is of growing interest for shape morphing, actuation, and wearable devices. Here, we report a facile fabrication method for creating soft robotic materials with embedded pneumatics that exhibit programmable shape morphing behavior. Using rotational multi-material 3D printing, asymmetrical core-shell filaments composed of elastomeric shells and fugitive cores are patterned in 1D and 2D motifs. By precisely controlling the nozzle design, rotation rate, and print path, one can control the local orientation, shape, and cross-sectional area of the patterned fugitive core along each printed filament. Once the elastomeric matrix is cured, the fugitive cores are removed, leaving behind embedded conduits that facilitate pneumatic actuation. Using a connected Fermat spirals pathing approach, one can automatically generate desired print paths required for more complex soft robots, such as hand-inspired grippers. Our integrated design and printing approach enables one to rapidly build soft robotic matter that exhibits myriad shape morphing transitions on demand.
Soft Condensed Matter (cond-mat.soft), Robotics (cs.RO)
33 pages, 5 main text figures, 4 supporting text figures, 10 movies (movie repository link - this https URL)
A new generation of effective core potentials: Selected lanthanides and heavy elements II
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Omar Madany, Benjamin Kincaid, Aqsa Shaikh, Elizabeth Morningstar, Lubos Mitas
We present a new set of correlation-consistent effective core potentials (ccECPs) for selected heavy $ s$ , $ p$ , $ d$ , and $ f$ -block elements significant in materials science and chemistry (Rb, Sr, Cs, Ba, In, Sb, Pb, Ru, Cd, La, Ce, and Eu). The ccECPs are designed using minimal Gaussian parameterization to achieve smooth and bounded potentials. They are expressed as a combination of averaged relativistic effective potentials (AREP) and effective spin-orbit (SO) terms, developed within a relativistic coupled-cluster framework. The optimization is driven by correlated all-electron (AE) atomic spectra, norm-conservation, and spin-orbit splittings, with considerations for plane wave cut-offs to ensure accuracy and viability across various electronic configurations. Transferability of these ccECPs is validated through testing on molecular oxides and hydrides, emphasizing discrepancies in molecular binding energies across a spectrum of bond lengths and electronic environments. The ccECPs demonstrate excellent agreement with AE reference calculations, attaining chemical accuracy in bond dissociation energies and equilibrium bond lengths, even in systems characterized by substantial relativistic and correlation effects. These ccECPs provide accurate and transferable framework for valence-only calculations.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
16 pages, 17 figures and 5 tables
Nucleation and Antiphase Twin Control in Bi$_2$Se$_3$ via Step-Terminated Al$_2$O$_3$ Substrates
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Alessandro R. Mazza, Jia Shi, Gabriel A. Vazquez-Lizardi, An-Hsi Chen, Kim Kisslinger, Debarghya Mallick, Sangsoo Kim, Qiangsheng Lu, T. Zac Ward, Vitalii Starchenko, Nicholas Cucciniello, Robert G. Moore, Gyula Eres, Yue Cao, Debangshu Mukherjee, Christopher Nelson, Danielle Reifsnyder Hickey, Fei Xue, Matthew Brahlek
The epitaxial synthesis of high-quality 2D layered materials is an essential driver of both fundamental physics studies and technological applications. Bi$ _2$ Se$ _3$ , a prototypical 2D layered topological insulator, is sensitive to defects imparted during the growth, either thermodynamically or due to the film-substrates interaction. In this study, we demonstrate that step-terminated Al$ _2$ O$ _3$ substrates with a high miscut angle (3$ ^\circ$ ) can effectively suppress a particular hard-to-mitigate defect, the antiphase twin. Systematic investigations across a range of growth temperatures and substrate miscut angles confirm that atomic step edges act as preferential nucleation sites, stabilizing a single twin domain. First principles calculations suggest that there is a significant energy barrier for twin boundary formation at step edges, supporting the experimental observations. Detailed structural characterization indicates that this twin-selectivity is lost through the mechanism of the 2D layers overgrowing the step edges, leading to higher twin density as the thickness increases. These findings highlight the complex energy landscape unique to 2D materials that is driven by the interplay between substrate topology, nucleation dynamics, and defect formation, and overcoming and controlling these are critical to improve material quality for quantum and electronic applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Higher-order topological phases protected by non-invertible and subsystem symmetries
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-26 20:00 EDT
Aswin Parayil Mana, Yabo Li, Hiroki Sukeno, Tzu-Chieh Wei
Higher-order topological phases with invertible symmetries have been extensively studied in recent years, revealing gapless modes localized on boundaries of higher codimension. In this work, we extend the framework of higher-order symmetry-protected topological (SPT) phases to include non-invertible symmetries. We construct a concrete model of a second-order SPT phase in $ 2+1$ dimensions that hosts symmetry-protected corner modes protected by a non-invertible symmetry. This construction is then generalized to a $ d^{th}$ -order SPT phase in $ d+1$ dimensions, featuring similarly protected corner modes. Additionally, we demonstrate a second-order SPT phase in $ 3+1$ dimensions exhibiting hinge modes protected by a non-invertible symmetry.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
57 pages, 17 figures
Multiparty entanglement loops in quantum spin liquids
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-05-26 20:00 EDT
Liuke Lyu, Deeksha Chandorkar, Samarth Kapoor, So Takei, Erik S. Sørensen, William Witczak-Krempa
Quantum spin liquids (QSLs) give rise to exotic emergent particles by weaving intricate entanglement patterns in the underlying electrons. Bipartite measures between subregions can detect the presence of anyons, but little is known about the full entanglement structure of QSLs. Here, we study the multiparty entanglement of QSLs via entanglement microscopy. We find that in contrast to conventional matter, the genuine multiparty entanglement (GME) between spins is absent in the smallest subregions, a phenomenon we call “entanglement frustration”. Instead, GME is more collective, and arises solely in loops. By exploiting exact results and large-scale numerics, we confirm these properties in various gapped and gapless QSLs realised in physically motivated Hamiltonians, as well as with string-net wavefunctions hosting abelian or non-abelian anyons. Our results shed new light on the phase diagram of Kitaev’s honeycomb model in a Zeeman field, and the Kagome Heisenberg model under various perturbations. Going beyond QSLs, we provide evidence that entanglement loops are a universal property of quantum gauge theories. This leads to a new understanding of fractionalization, and the means by which gauge bosons encode quantum information.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
27 pages, 15 figures
Tuning Thermal Conductivity and Electron-Phonon Interactions in Carbon and Boron Nitride Moiré Diamanes via Twist Angle Manipulation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Rustam Arabov, Nikita Rybin, Victor Demin, Mikhail Polovinkin, Alexander Kvashnin, Leonid Chernozatonskii, Alexander Shapeev
We have investigated the effect of interlayer twist angle on the in-plane lattice thermal conductivity and the band gap renormalization in diamane-like hydrogenated bilayer boron nitride (BN) and graphene Moiré lattices. Machine learning moment tensor potentials were used for calculating energies and forces of interatomic interactions. The methods based on the solution of the Boltzmann transport equation (BTE) for phonons and the Green-Kubo (GK) formula were utilized to obtain LTC values. The 20-40% difference in LTC values obtained with GK and BTE-based methods showed the importance of high-order anharmonic contributions to LTC in the BN-based lattice with $ \theta=21.8^\circ$ and all considered graphene-based structures. Significant reduction (by 4.5 - 9 times) of the in-plane LTC with the increase in the twist angle was observed in the Moiré lattices. This LTC reduction is caused by the decrease of phonon lifetimes. The phonon lifetimes decrease due to the growth of structural disorder in the Moiré lattices with the twist angle increase. We also show that the growth of disorder with increasing twist angle affects the electron-phonon interactions. This leads to higher band gap renormalization (induced by classical nuclei motion) at higher twist angles. High band gap renormalization (even at T = 0 K) values obtained considering the quantum nuclear effects are caused by the high frequencies of lattice vibrations in the Moiré lattices. These high frequencies are caused by the presence of light hydrogen atoms on the surfaces of the structures. Understanding of the twist-angle-induced disorder effect on phonon properties, LTC and electron-phonon coupling in the Moiré lattices provides a fundamental basis for manipulating the thermal and electronic properties of these structures, making them promising for applications in thermoelectrics, microelectronics and optoelectronics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Effect of Fluorine doping on the electrocatalytic properties of Nb2O5 for H2O2 electrogeneration
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Aline B. Trench, João Paulo C. Moura, Caio Machado Fernandes, Mauro C. Santos
The oxygen reduction reaction (ORR) via the 2-electron mechanism is an efficient way to produce hydrogen peroxide (H2O2) under mild conditions. This study examines the modification of Vulcan XC72 carbon with fluorine (F)-doped niobium oxide (Nb2O5) nanoparticles at varying molar ratios (0, 0.005, 0.01, 0.02). The F-doped Nb2O5 nanoparticles were synthesized using the oxidizing peroxide method and then incorporated into Vulcan XC72 carbon via impregnation. Characterization techniques included X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurements, and X-ray photoelectron spectroscopy (XPS). Electrochemical evaluation using the rotating ring disk electrode method revealed that Vulcan XC72 modified with 1.0% F-doped Nb2O5 exhibited the best ORR performance. When used as a gas diffusion electrode, this electrocatalyst produced more H2O2 at all applied potentials than the pure and Nb2O5-modified Vulcan XC72 carbon. At potentials of -0.7 V and -1.3 V, the proposed electrocatalyst achieved H2O2 yields 65% and 98% higher than the Nb2O5-modified electrocatalyst. Furthermore, it presented lower energy consumption and higher current efficiency than the other electrocatalysts compared in this study. The enhanced performance is attributed to F doping, which increased Nb2O5 lattice distortion and disorder, improving electron availability for ORR. Additionally, F-doped electrocatalysts exhibited more oxygenated species and greater hydrophilicity, facilitating O2 adsorption, transport, and electron transfer. These properties significantly enhanced H2O2 electrogeneration efficiency while reducing energy consumption.
Materials Science (cond-mat.mtrl-sci)
INN-FF: A Scalable and Efficient Machine Learning Potential for Molecular Dynamics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-05-26 20:00 EDT
Taskin Mehereen, Sourav Saha, Intesar Jawad Jaigirdar, Chanwook Park
The ability to accurately model interatomic interactions in large-scale systems is fundamental to understanding a wide range of physical and chemical phenomena, from drug-protein binding to the behavior of next-generation materials. While machine learning interatomic potentials (MLIPs) have made it possible to achieve ab initio-level accuracy at significantly reduced computational cost, they still require very large training datasets and incur substantial training time and expense. In this work, we propose the Interpolating Neural Network Force Field (INN-FF), a novel framework that merges interpolation theory and tensor decomposition with neural network architectures to efficiently construct molecular dynamics potentials from limited quantum mechanical data. Interpolating Neural Networks (INNs) achieve comparable or better accuracy than traditional multilayer perceptrons (MLPs) while requiring orders of magnitude fewer trainable parameters. On benchmark datasets such as liquid water and rMD17, INN-FF not only matches but often surpasses state-of-the-art accuracy by an order of magnitude, while achieving significantly lower error when trained on smaller datasets. These results suggest that INN-FF offers a promising path toward building efficient and scalable machine-learned force fields.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Stochastic agent-based Monte Carlo simulations for reaction-diffusion models, population dynamics, and epidemic spreading
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-05-26 20:00 EDT
Mohamed Swailem, Ulrich Dobramysl, Ruslan Mukhamadiarov, Uwe C. Täuber
We provide a succinct overview of the implementation of Monte Carlo algorithms based on Markovian stochastic dynamics to study interacting and reacting many-particle systems away from thermal equilibrium. Such agent-based computer simulations constitute an effective tool to introduce undergraduate and beginning graduate students to current frontier research without requiring much prior knowledge or experience: Starting from direct visualization of simulation data, students may gain immediate insight into emerging macroscopic features of a complex model system and subsequently apply more sophisticated data analysis to quantitatively characterize its often rich dynamical properties, both in stationary and transient regimes. We utilize numerical investigations of paradigmatic reaction-diffusion systems, as well as stochastic models for population dynamics and epidemic spreading, to exemplify how interdisciplinary computational research can be effectively utilized in bottom-up undergraduate and graduate education through learning by doing. In addition, we give helpful hints for the practical setup of Monte Carlo simulation algorithms, provide sample codes, explain some typical data analysis tools, and describe various potential error sources and pitfalls, with tips for avoiding them.
Statistical Mechanics (cond-mat.stat-mech), Populations and Evolution (q-bio.PE)
66 pages, 18 figures, submitted to American Journal of Physics (2025)