CMP Journal 2025-01-25
Statistics
arXiv: 66
arXiv
Continuously controllable dissipative and coherent couplings by the interaction between anti-resonance and multiple magnons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Zhenhui Hao, Yuping Yao, Kang An, Xiling Li, Chi Zhang, Guozhi Chai
Weexperimentally realize the continuously controllable dissipative coupling and coherent coupling induced by different magnon modes and the same anti-resonance. It has been observed that the weaker the microwave magnetic field distribution of the magnon mode in magnetic materials, the more likely dissipative coupling is to occur. Conversely, stronger magnetic field distributions favor coherent coupling. Based on this principle, we have designed and implemented a system that alternates between dissipative and coherent coupling regimes. It allows microwave signals to be selectively transmitted over a large applied magnetic field range at the frequency of anti-resonance. Our experimental achievements may promote the construction of new magnonics devices like magnetic-tuning switch.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 6 figures
Imaging Topological Defect Dynamics Mediating 2D Skyrmion Lattice Melting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-24 20:00 EST
Raphael Gruber, Jan Rothörl, Simon M. Fröhlich, Maarten A. Brems, Fabian Kammerbauer, Maria-Andromachi Syskaki, Elizabeth M. Jefremovas, Sachin Krishnia, Asle Sudbø, Peter Virnau, Mathias Kläui
Topological defects are the key feature mediating 2D phase transitions. However, both resolution and tunability have been lacking to access the dynamics of the transitions. With dynamic Kerr microscopy, we directly capture the melting of a confined 2D magnetic skyrmion lattice with high resolution in real-time and -space. Skyrmions in magnetic thin films are two-dimensional, topologically non-trivial quasi-particles that provide rich dynamics as well as unique tunability as an essential ingredient for controlling phase behavior: We tune the skyrmion size and effective temperature on the fly to drive the two-step melting through an intermediate hexatic regime between the solid lattice and the isotropic liquid. We quantify the characteristic occurrence of topological defects mediating the transitions and reveal the so-far inaccessible dynamics of the lattice dislocations. The full real-time and -space imaging reveals the diffusion coefficient of the dislocations, which we find to be orders of magnitudes higher than that of the skyrmions.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Random Quantum Circuits with Time-Reversal Symmetry
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-24 20:00 EST
Kabir Khanna, Abhishek Kumar, Romain Vasseur, Andreas W. W. Ludwig
Time-reversal (TR) symmetry is crucial for understanding a wide range of physical phenomena, and plays a key role in constraining fundamental particle interactions and in classifying phases of quantum matter. In this work, we introduce an ensemble of random quantum circuits that are representative of the dynamics of generic TR-invariant many-body quantum systems. We derive a general statistical mechanics model describing entanglement, many-body quantum chaos and quantum information dynamics in such TR-invariant circuits. As an example of application of our formalism, we study the universal properties of measurement-induced phase transitions (MIPT) in monitored TR-invariant systems, with measurements performed in a TR-invariant basis. We find that TR-invariance of the unitary part of the dynamics does not affect the universality class, unless measurement outcomes are post-selected to satisfy the global TR-invariance of each quantum trajectory. We confirm these predictions numerically, and find, for both generic and Clifford-based evolutions, novel critical exponents in the case of ``strong'', i.e. global TR-invariance where each quantum trajectory is TR-invariant.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Physics (quant-ph)
24 pages, 9 figures
Quantum chaos at finite temperature in local spin Hamiltonians
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-24 20:00 EST
Christopher M. Langlett, Cheryne Jonay, Vedika Khemani, Joaquin F. Rodriguez-Nieva
Understanding the emergence of chaos in many-body quantum systems away from semi-classical limits, particularly in spatially local interacting spin Hamiltonians, has been a long-standing problem. In these intrinsically quantum regimes, quantum chaos has been primarily understood through the correspondence between the eigensystem statistics of midspectrum eigenstates and the universal statistics described by random matrix theory (RMT). However, this correspondence no longer holds for finite-temperature eigenstates. Here we show that the statistical properties of finite-temperature eigenstates of quantum chaotic Hamiltonians can be accurately described by pure random states constrained by a local charge, with the average charge density of the constrained random state ensemble playing the same role as the average energy density of the eigenstates. By properly normalizing the energy density using a single Hamiltonian-dependent parameter that quantifies the typical energy per degree of freedom, we find excellent agreement between the entanglement entropy statistics of eigenstates and that of constrained random states. Interestingly, in small pockets of Hamiltonian parameter phase space which we previously identified as `maximally chaotic' [PRX 14, 031014 (2024)], we find excellent agreement not only at the level of the first moment, including O(1) corrections, but also at the level of statistical fluctuations. These results show that notions of maximal chaos -- in terms of how much randomness eigenstates contain -- can still be defined at finite temperature in physical Hamiltonian models away from semi-classical and large-\(N\) limits.
Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
7+3 pages, 3+2 figures
Landau levels in the mixed state of two-dimensional nodal superconductors: models, featured magneto-optical response and quantized thermal Hall effect
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-24 20:00 EST
Zhihai Liu, Bin Wang, Luyang Wang
Landau quantization of low-energy quasiparticles (QPs) in the mixed state of gapless superconductors is a celebrated problem. So far, the only superconducting system that has been shown to host Landau levels (LLs) of Bogoliubov QPs is the Weyl superconductor. Here, we first investigate the QPs in the mixed state of two Weyl superconductors, an intrinsic one and a heterostructure one, and reveal that the QP states in the former do not form LLs, in contrast to those in the latter where LLs of QPs are shown to exist. The key is whether the low-energy Hamiltonian respects a generalized chiral symmetry. Following the analysis, we show that a twodimensional superconducting system -- a topological insulator-superconductor heterostructure respecting the generalized chiral symmetry -- exhibits LLs with Chern number \(\pm 1\) in the mixed state. We also show featured responses resulting from the LLs, including peaked magneto-optical conductivity and quantized thermal Hall conductivity, which could be used as experimental probes to detect LLs in superconductors.
Superconductivity (cond-mat.supr-con)
7 pages, 5 figures
Coexistence of Kondo Coherence and Localized Magnetic Moments in the Normal State of Molten Salt-Flux Grown UTe2
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-24 20:00 EST
N. Azari, M. Yakovlev, S. R. Dunsiger, O. P. Uzoh, E. Mun, B. M. Huddart, S. J. Blundell, M. M. Bordelon, S. M. Thomas, J. D. Thompson, P. F. S. Rosa, J. E. Sonier
The development of Kondo lattice coherence in UTe2 leads to the formation of a heavy Fermi liquid state from which superconductivity emerges at lower temperature. In Kondo lattice systems, the nuclear magnetic resonance (NMR) and muon Knight shift have proven to be particularly sensitive to the properties of the developing heavy-electron fluid. Here we report muon Knight shift measurements on high-quality UTe2 single crystals grown by a molten salt-flux method. Together with previous data from a single crystal grown by a chemical-vapor transport method, our results show the contribution of the heavy-electron liquid to the muon Knight shift increases below a crossover temperature T~ 30 K in accord with a universal scaling function of T/Tfor heavy-fermion materials. An observed departure from this universal scaling below a temperature T ~ 12 K at certain muon stopping sites signifies a reversal of the Kondo hybridization and a relocalization of U 5f moments with an antiferromagnetic coupling. The preservation of universal scaling at a different muon site demonstrates a coexistence of itinerant and localized 5f electron states preceding the superconducting phase transition.
Superconductivity (cond-mat.supr-con)
8 pages, 4 figures
Phys. Rev. B 111, 014513 (2025)
Topological constraints on self-organisation in locally interacting systems
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-24 20:00 EST
Francesco Sacco, Dalton A R Sakthivadivel, Michael Levin
All intelligence is collective intelligence, in the sense that it is made of parts which must align with respect to system-level goals. Understanding the dynamics which facilitate or limit navigation of problem spaces by aligned parts thus impacts many fields ranging across life sciences and engineering. To that end, consider a system on the vertices of a planar graph, with pairwise interactions prescribed by the edges of the graph. Such systems can sometimes exhibit long-range order, distinguishing one phase of macroscopic behaviour from another. In networks of interacting systems we may view spontaneous ordering as a form of self-organisation, modelling neural and basal forms of cognition. Here, we discuss necessary conditions on the topology of the graph for an ordered phase to exist, with an eye towards finding constraints on the ability of a system with local interactions to maintain an ordered target state. By studying the scaling of free energy under the formation of domain walls in three model systems -- the Potts model, autoregressive models, and hierarchical networks -- we show how the combinatorics of interactions on a graph prevent or allow spontaneous ordering. As an application we are able to analyse why multiscale systems like those prevalent in biology are capable of organising into complex patterns, whereas rudimentary language models are challenged by long sequences of outputs.
Statistical Mechanics (cond-mat.stat-mech), Machine Learning (cs.LG), Cell Behavior (q-bio.CB)
9+3 pages, four figures, four tikzpictures. To appear in Philos Trans R Soc A
Duality breaking, mobility edges, and the connection between topological Aubrey-Andr'e and quantum Hall insulators in atomic wires with fermions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Bar Alluf, C. A. R. Sa de Melo
It is well known that the Aubry-Andr{é} model lacks mobility edges due to its energy-independent self-duality but may exhibit edge states. When duality is broken, we show that mobility regions arise and non-trivial topological phases emerge. By varying the degree of duality breaking, we identify mobility regions and establish a connection between Aubry-Andr{é} atomic wires with fermions and quantum Hall systems for a family of Hamiltonians that depends on the relative phase of laser fields, viewed as a synthetic dimension. Depending on the filling factor and the degree of duality breaking, we find three classes of non-trivial phases: conventional topological insulator, conventional topological Aubry-Andr{é} insulator, and unconventional (hybrid) topological Aubry-Andr{é} insulator. Finally, we discuss appropriate Chern numbers that illustrate the classification of topological phases of localized fermions in atomic wires.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Disordered Systems and Neural Networks (cond-mat.dis-nn)
16 pages, 14 figures
Ground States of the Mean-Field Spin Glass with 3-Spin Couplings
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-24 20:00 EST
Stefan Boettcher, Ginger E. Lau (Emory U)
We use heuristic optimization methods in extensive computations to determine with low systematic error ground state configurations of the mean-field \(p\)-spin glass model with \(p=3\). Here, all possible triplets in a system of \(N\) Ising spins are connected with a bond. This model has been of recent interest, since it exhibits the ``overlap gap condition'', which should make it prohibitive to find ground states asymptotically with local search methods when compared, for instance, with the \(p=2\) case better-known as the Sherrington-Kirkpatrick model (SK). Indeed, it proves more costly to find good approximations for \(p=3\) than for SK, even for our heuristic. Compared to SK, the ground-state behavior for \(p=3\) is quite distinct also in other ways. For SK, finite-size corrections for large system sizes \(N\to\infty\) of both, the ensemble average over ground state energy densities and the width of their distribution, vary anomalously with non-integer exponents. In the \(p=3\) case here, the energy density and its distribution appear to scale with \(\ln N/N\) and \(1/N\) corrections, respectively. The distribution itself is consistent with a Gumbel form. Even more stark is the contrast for the bond-diluted case, where SK has shown previously a notable variation of the anomalous corrections exponent with the bond density, while for \(p=3\) no such variation is found here. Hence, for the 3-spin model, all measured corrections scale the same as for the random energy model (REM), corresponding to \(p=\infty\). This would suggest that all \(p\)-spin models with \(p\geq3\) exhibit the same ground-state corrections as in REM.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Quantum Physics (quant-ph)
RevTex 4.2, 5 pages, 5 pdf-figures incl., related information can be found at this https URL
Accelerating Discovery of Solid-State Thin-Film Metal Dealloying for 3D Nanoarchitecture Materials Design through Laser Thermal Gradient Treatment
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Cheng-Chu Chung, Ruipeng Li, Gabriel M. Veith, Honghu Zhang, Fernando Camino, Ming Lu, Nikhil Tiwale, Sheng Zhang, Kevin Yager, Yu-chen Karen Chen-Wiegart
Thin-film solid-state metal dealloying (thin-film SSMD) is a promising method for fabricating nanostructures with controlled morphology and efficiency, offering advantages over conventional bulk materials processing methods for integration into practical applications. Although machine learning (ML) has facilitated the design of dealloying systems, the selection of key thermal treatment parameters for nanostructure formation remains largely unknown and dependent on experimental trial and error. To overcome this challenge, a workflow enabling high-throughput characterization of thermal treatment parameters while probing local nanostructures of thin-film samples is needed. In this work, a laser-based thermal treatment is demonstrated to create temperature gradients on single thin-film samples of Nb-Al/Sc and Nb-Al/Cu. This continuous thermal space enables observation of dealloying transitions and the resulting nanostructures of interest. Through synchrotron X-ray multimodal and high-throughput characterization, critical transitions and nanostructures can be rapidly captured and subsequently verified using electron microscopy. The key temperatures driving chemical reactions and morphological evolutions are clearly identified within this framework. While the oxidation process may contribute to nanostructure formation during thin-film treatment, the dealloying process at the dealloying front involves interactions solely between the dealloying elements, highlighting the availability and viability of the selected systems. This approach enables efficient exploration of the dealloying process and validation of ML predictions, thereby accelerating the discovery of thin-film SSMD systems with targeted nanostructures.
Materials Science (cond-mat.mtrl-sci)
The main content contains 6 figures within 25 pages. The supporting information includes 5 figures within 5 pages
Catalytic Nanoparticles: An Introduction
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Jairo Rondón, Angel Gonzalez-Lizardo, Claudio Lugo
This study explores the transformative potential of nanocatalysts, emphasizing their pivotal role in catalysis and material science. Key synthesis techniques, including chemical reduction and hybrid methods, are highlighted for their ability to control particle size and enhance stability. Applications in environmental remediation, fuel quality improvement, and renewable energy showcase the broad impact of nanocatalysts. Despite challenges in scalability and stabilization, advancements in bimetallic configurations and electro-steric approaches demonstrate significant progress. This research underscores nanocatalysts' promise for sustainable industrial processes and global challenges.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
9 pages
Field induced density wave in a kagome superconductor
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-24 20:00 EST
Md Shafayat Hossain, Qi Zhang, Julian Ingham, Jinjin Liu, Sen Shao, Yangmu Li, Yuxin Wang, Bal K. Pokharel, Zi-Jia Cheng, Yu-Xiao Jiang, Maksim Litskevich, Byunghoon Kim, Xian Yang, Yongkai Li, Tyler A. Cochran, Yugui Yao, Dragana Popović, Zhiwei Wang, Guoqing Chang, Ronny Thomale, Luis Balicas, M. Zahid Hasan
On the kagome lattice, electrons benefit from the simultaneous presence of band topology, flat electronic bands, and van Hove singularities, forming competing or cooperating orders. Understanding the interrelation between these distinct order parameters remains a significant challenge, leaving much of the associated physics unexplored. In the kagome superconductor KV3Sb5, which exhibits a charge density wave (CDW) state below T = 78 K, we uncover an unpredicted field-induced phase transition below 6 K. The observed transition is marked by a hysteretic anomaly in the resistivity, nonlinear electrical transport, and a change in the symmetry of the electronic response as probed via the angular dependence of the magnetoresistivity. These observations surprisingly suggest the emergence of an unanticipated broken symmetry state coexisting with the original CDW. To understand this experimental observation, we developed a theoretical minimal model for the normal state inside the high-temperature parent CDW phase where an incommensurate CDW order emerges as an instability sub-leading to superconductivity. The incommensurate CDW emerges when superconducting fluctuations become fully suppressed by large magnetic fields. Our results suggest that, in kagome superconductors, quantum states can either coexist or are nearly degenerate in energy, indicating that these are rich platforms to expose new correlated phenomena.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Using Principal Component Analysis to Distinguish Different Dynamic Phases in Superconducting Vortex Matter
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-24 20:00 EST
C.J.O. Reichhardt, D. McDermott, C. Reichhardt
Vortices in type-II superconductors driven over random disorder are known to exhibit a remarkable variety of distinct nonequilibrium dynamical phases that arise due to the competition between vortex-vortex interactions, the quenched disorder, and the drive. These include pinned states, elastic flows, plastic or disordered flows, and dynamically reordered moving crystal or moving smectic states. The plastic flow phases can be particularly difficult to characterize since the flows are strongly disordered. Here we perform principal component analysis (PCA) on the positions and velocities of vortex matter moving over random disorder for different disorder strengths and drives. We find that PCA can distinguish the known dynamic phases as well as or better than previous measures based on transport signatures or topological defect densities. In addition, PCA recognizes distinct plastic flow regimes, a slowly changing channel flow and a moving amorphous fluid flow, that do not produce distinct signatures in the standard measurements. Our results suggest that this position and velocity based PCA approach could be used to characterize dynamic phases in a broader class of systems that exhibit depinning and nonequilibrium phase transitions.
Superconductivity (cond-mat.supr-con), Statistical Mechanics (cond-mat.stat-mech)
21 pages, 22 figures
Ferromagnetic Semiconductor Nanotubes with Room Curie Temperatures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Realizing ferromagnetic semiconductors with room Curie temperature \(T\rm_C\) remains a challenge in spintronics. Inspired by the recent experimental progress on the nanotubes based on 2D van der Waals non-magnetic transition-metal dichalcogenides, magnetic nanotubes based on monolayer ferromagnetic materials are highly possible. Here, we proposed a way how to obtain high \(T\rm_C\) ferromagnetic semiconductor nanotubes. Some high \(T\rm_C\) ferromagnetic semiconductors are predicted in the MX\(_2\) nanotubes (M = V, Cr, Mn, Fe, Co, Ni; X = S, Se, Te), including CrS\(_2\) and CrTe\(_2\) zigzag nanotubes with the diameter of 18 unit cells showing \(T\rm_C\) above 300 K. In addition, due to the strain gradient in walls of nanotubes, an electrical polarization at level of \(0.1\) eV/Å~inward of the radial direction is obtained. Our results not only present novel ferromagnetic semiconductor nanotubes with room Curie temperature but also be indicative of how to obtain such nanotubes based on experimentally obtained 2D high \(T\rm_C\) ferromagnetic metals.
Materials Science (cond-mat.mtrl-sci)
Effects of valley splitting on resonant-tunneling readout of spin qubits
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
The effect of valley splitting on the readout of qubit states is theoretically investigated in a three-quantum-dot (QD) system. A single unit of the three-QD system consists of qubit-QDs and a channel-QD that is connected to a conventional transistor. The nonlinear source--drain current characteristics under resonant-tunneling effects are used to distinguish different qubit states. Using nonequilibrium Green functions, the current formula for the three-QD system is derived when each QD has two valley energy levels. Two valley states in each QD are considered to be affected by variations in the fabrication process. We found that when valley splitting is smaller than Zeeman splitting, the current nonlinearity can improve the readout, provided that the nonuniformity of the valley energy levels is small. Conversely, when the valley splitting is larger than the Zeeman splitting, the nonuniformity degraded the readout. In both cases, we showed that there are regions where the measurement time \(t_{\rm meas}\) is much less than the decoherence time \(t_{\rm dec}\) such that \(t_{\rm dec}/t_{\rm meas}>100\). This suggests that less than 1% measurement error is anticipated, which opens up the possibility for implementing surface codes even in the presence of valley splitting.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
17 pages, 18 figures
Stability of the long-range corrected exchange-correlation functional in time-dependent density-functional theory
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Jared R. Williams, Carsten A. Ullrich
Excitonic effects in the optical absorption spectra of solids can be described with time-dependent density-functional theory (TDDFT) in the linear-response regime, using a simple class of approximate, long-range corrected (LRC) exchange-correlation functionals. It was recently demonstrated that the LRC approximation can also be employed in real-time TDDFT to describe exciton dynamics. Here, we investigate the numerical stability of the time-dependent LRC approach using a two-dimensional model solid. It is found that the time-dependent Kohn-Sham equation with an LRC vector potential becomes more and more prone to instabilities for increasing exciton binding energies. The origin of these instabilities is traced back to time-averaged violations of the zero-force theorem, which leads to a simple and robust numerical stabilization scheme. This explains and justifies a recently proposed method by Dewhurst et al., arXiv:2401.16140.
Materials Science (cond-mat.mtrl-sci)
16 pages, 11 figures
Observation of molecular and polymeric nitrogen stuffed NaCl ionic layers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Ping Ning, Yifan Tian, Guangtao Liu, Hongbo Wang, Qingyang Hu, Hanyu Liu, Mi Zhou, Yanming Ma
Sodium chloride (NaCl), a ubiquitous and chemically stable compound, has been considered inert under ambient conditions. Its typical B1 structure is highly isotropic without preferential direction, favoring the growth of a three-dimensional network of strong Na-Cl ionic bonds. Here, we employ first-principles structural searching and synchrotron X-ray diffraction to unravel an unexpected chemical reaction between NaCl and N2 to produce a hybrid salt-NaCl(N2)2, where N2 molecules break the isotropic NaCl structure into two-dimensional layers upon synthesis at 50 GPa. In contrast to the insulating properties of pristine NaCl, the electronic bandgap of the N2-stuffed NaCl narrowed to 1.8 eV, becoming an indirect bandgap semiconductor. Further compression to 130 GPa induced the polymerization of N atoms into zigzag N-chains. Our findings not only demonstrate the possibility of unusual N-chemistry under extreme conditions, but also suggest a feasible approach for the design of layered NaCl frameworks to modulate the polymerization of nitrogen.
Materials Science (cond-mat.mtrl-sci)
9 pages, 3 figures
Spontaneous Donor Defects and Voltage-Assisted Hole Doping in Beta-Gallium Oxides under Multiple Epitaxy Conditions
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Chenxi Nie, Kai Liu, Chengxuan Ke, Xisong Jiang, Yifeng He, Yonghong Deng, Yanhua Yan, Guangfu Luo
Beta-phase gallium oxide (beta-Ga2O3) is prone to the spontaneous formation of donor defects but poses a formidable challenge in achieving high-quality p-type doping, mainly due to its exceptionally low valence band maximum (VBM). In this study, we utilize first-principles computations to investigate the origin of spontaneous donor defects in beta-Ga2O3 grown by three typical techniques: molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD), and halide vapor phase epitaxy (HVPE). Our findings elucidate that the primary donor defects vary with the growth techniques, specifically Gai3+ for MBE, Hi+ and CGa+ for MOCVD, and (2VGa+Gai+2VO)+ and ClO+ for HVPE under unintentionally doped conditions. Employing a theoretically proposed voltage-assisted doping method, we computationally demonstrate that the dominant spontaneous donors can be significantly reduced accompanied by a noticeable increase in acceptors, leading to a stepwise reduction of Fermi level to 0.52, 0.88, and 2.10 eV above VBM for the MOCVD, HVPE, and MBE methods, and a hole concentration of 8.5^17, 8.7^11, and 2.7^-9 cm-3, respectively, at room temperature without the use of external dopants. By introducing Mg doping, we further reduce the Fermi level for both the MBE and HVPE experiments.
Materials Science (cond-mat.mtrl-sci)
Model for the commensurate charge-density waves in under-hole-doped cuprate superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-24 20:00 EST
Jacob Morrissey, Timothy J.Haugan, Richard A. Klemm
A simple model of the commensurate charge-density wave (CCDW) portion of the underdoped pseudogap regions of monolayer Bi\(_2\)Sr\(_{2-x}\)La\(_x\)CuO\(_{6-x}\) (Bi2201), bilayer Bi\(_2\)Sr\(_2\)CaCu\(_2\)O\(_{8+\delta}\) (Bi2212), and trilayer Bi\(_2\)Sr\(_2\)Ca\(_2\)Cu\(_3\)O\(_{10+\delta}\) (Bi2223) cuprate superconductors is presented and studied. Above the superconducting transition temperature \(T_c\) but below the pseudogap transition temperature \(T_p > T_c\), the CCDW forms on the oxygen sites in the CuO\(_2\) layers with excess charges of \(\pm\delta e\), where \(e\) is the electronic charge, forming on alternating oxygen sites. This model is equivalent to \(N\)-layer versions of the two-dimensional Ising model for spins on a square lattice with repulsive interactions \(J' , J>0\) between near-neighbor inter- and intralayer sites, respectively. For strong coupling, we show analytically for sections of \(L\times M\times N\) sites that the partition function in the \(J'\rightarrow\pm \infty\) limits reduces to that for an effective single layer with \(L\times M\) sites and \(J\) replaced by \(NJ\). The CCDW is therefore strongly enhanced and stabilized by multilayer structures, likely accounting for the enhanced THz emission observed from the intrinsic Josephson junctions in underdoped Bi2212 mesas and for the many experiments on Bi2212 and related compounds purporting to provide evidence for a superconducting order parameter with \(d_{x^2-y^2}\)-wave symmetry.
Superconductivity (cond-mat.supr-con)
10 pages, 16 figures
Probing scattering of Raman phonons on magnetic and electronic excitations in pyrochlores Nd\(_2\)Zr\(_2\)O\(_7\) and Nd\(_2\)Ir\(_2\)O\(_7\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-24 20:00 EST
Sami Muhammad, Yuanyuan Xu, Christos Kakogiannis, Takumi Ohtsuki, Yang Qiu, Satoru Nakatsuji, Eli Zoghlin, Stephen D. Wilson, Natalia Drichko
Magnetic rare earth atoms on pyrochlore lattice can produce such exotic magnetic states as spin ice and quantum spin ice. These states are a result of the frustration in the pyrochlore lattice, as well as crystal field degrees of freedom of rare earth atoms, and their interactions with the lattice. Raman scattering spectroscopy, which possess high spectral resolution and can easily access broad energy and temperature ranges, is an optimum tool to study these excitations and their interactions. In this work we follow Raman scattering of zone center phonons and crystal field excitations of Nd\(^{3+}\) in Nd\(_2\)Zr\(_2\)O\(_7\) and Nd\(_2\)Ir\(_2\)O\(_7\) in the temperature range where these materials are paramagnetic. A comparison between an insulating Nd\(_2\)Zr\(_2\)O\(_7\) and semimetallic Nd\(_2\)Ir\(_2\)O\(_7\) materials allow us to distinguish between scattering of phonons on other phonons, crystal field excitations, and electrons, highlighting interactions between these degrees of freedom.
Strongly Correlated Electrons (cond-mat.str-el)
Stabilizing Single-Atom Catalysts on Metastable Phases of Transition Metal Dichalcogenides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Lina Wang, Zhenhai Wen, Guangfu Luo
Single-atom catalysts have attracted significant attention due to their exceptional atomic utilization and high efficiency in a range of catalytic reactions. However, these systems often face thermodynamic instability, leading to agglomeration under operational conditions. In this study, we investigate the interactions of twelve types of catalytic atoms (Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, Au, and Bi) on three crystalline phases (1T, 1T', and 2H) of six transition metal dichalcogenide layers (MoS2, MoSe2, MoTe2, WS2, WSe2, and WTe2) based on first-principles calculations. We ultimately identify 82 stable single-atom systems that thermodynamically prevent the formation of metal clusters on these substrates. Notably, our findings reveal that the metastable 1T and 1T' phases significantly enhance the binding strength with single atoms and promote their thermodynamic stability. This research offers valuable insights into the design of stable single-atom systems and paves the way for discovering innovative catalysts in the future.
Materials Science (cond-mat.mtrl-sci)
The Journal of Physical Chemistry Letters 16, 969 (2025)
Single crystal growth of 1T-VSe\(_2\) by molten salt flux method
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Muhammed Anees K T, Souvik Kumar Rana, Abinash Das, Moumita Nandi
VSe\(_2\) is a highly promising van der Waals (vdW) material for applications in electronics, spintronics, and optoelectronics. Here, we report single crystal growth of 1T-VSe\(_2\) by flux method using eutectic of NaCl/KCl molten salt. The typical size of as-grown VSe\(_2\) single crystals is 5 \(\times\) 4 \(\times\) 0.1~mm\(^3\). The elemental composition and homogeneity of the crystals were examined by energy dispersive x-ray spectroscopy, which is consistent with the stoichiometric ratio of VSe\(_2\). The crystallographic [001] direction has been determined by x-ray diffraction. Raman measurement confirms that the 1T phase of VSe\(_2\) has been formed. Temperature-dependent resistivity measurement exhibits a transition around 104 K due to the formation of the charge density wave phase.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
4 pages, 5 figures
Liquid water transport model in hydrophilic granular : Preliminary validation with drying rate of hierarchical granular
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-24 20:00 EST
Hyuga Yasuda, Hiroaki Katsuragi, Makoto Katsura
The drying rate profile of granular beds can be divided into the constant rate period (CRP), which is characterized by a nearly constant drying rate, and the falling rate period (FRP), in which the drying rate rapidly decays. In order to explain this behavior quantitatively, we proposed a simple one-dimensional power law model in which the product of the water permeability and the pressure gradient is assumed to be proportional to the cube of the saturation. To test this model, we measured the drying rates of glass beads and hierarchical granular materials produced by sintering and breaking glass beads. Our results and those of previous experiments showed consistency with the power law. The obtained proportional constant of the experimental power law also shows a rough agreement with that estimated from previous studies on water permeability and capillary pressure. Drying behavior in FRP also agrees with our model in some points. The remnant deviation of the model from experimental results may be attributed to the inhomogeneity of granular media, which was qualitatively verified.
Soft Condensed Matter (cond-mat.soft)
23 pages, 18 figures, to be published in Physical Review Fluids
Read out the fermion parity of a potential artificial Kitaev chain utilizing a transmon qubit
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Enna Zhuo, Xiaozhou Yang, Yuyang Huang, Zhaozheng Lyu, Ang Li, Bing Li, Yunxiao Zhang, Xiang Wang, Duolin Wang, Yukun Shi, Anqi Wang, E.P.A.M. Bakkers, Xiaodong Han, Xiaohui Song, Peiling Li, Bingbing Tong, Ziwei Dou, Guangtong Liu, Fanming Qu, Jie Shen, Li Lu
Artificial Kitaev chains have emerged as a promising platform for realizing topological quantum computing. Once the chains are formed and the Majorana zero modes are braided/fused, reading out the parity of the chains is essential for further verifying the non-Abelian property of the Majorana zero modes. Here we demonstrate the feasibility of using a superconducting transmon qubit, which incorporates an end of a four-site quantum dot-superconductor chain based on a Ge/Si nanowire, to directly detect the singlet/doublet state, and thus the parity of the entire chain. We also demonstrate that for multiple-dot chains there are two types of 0-{} transitions between different charging states: the parity-flip 0-{} transition and the parity-preserved 0-{} transition. Furthermore, we show that the inter-dot coupling, hence the strengths of cross Andreev reflection and elastic cotunneling of electrons, can be adjusted by local electrostatic gating in chains fabricated on Ge/Si core-shell nanowires. Our exploration would be helpful for the ultimate realization of topological quantum computing based on artificial Kitaev chains.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
Liquid Metal-Exfoliated SnO\(_2\)-Based Mixed-dimensional Heterostructures for Visible-to-Near-Infrared Photodetection
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Shimul Kanti Nath, Nitu Syed, Wenwu Pan, Yang Yu, Dawei Liu, Michael P. Nielsen, Jodie Yuwono, Priyank Kumar, Yan Zhu, David L. Cortie, Chung K. Nguyen, Lan Fu, Ann Roberts, Lorenzo Faraone, Nicholas J. Ekins-Daukes, Wen Lei
Ultra-thin two-dimensional (2D) materials have gained significant attention for making next-generation optoelectronic devices. Here, we report a large-area heterojunction photodetector fabricated using a liquid metal-printed 2D \(\text{SnO}_2\) layer transferred onto CdTe thin films. The resulting device demonstrates efficient broadband light sensing from visible to near-infrared wavelengths, with enhanced detectivity and faster photo response than bare CdTe photodetectors. Significantly, the device shows a nearly \(10^5\)-fold increase in current than the dark current level when illuminated with a 780 nm laser and achieves a specific detectivity of around \(10^{12} \, \text{Jones}\), nearly two orders of magnitude higher than a device with pure CdTe thin film. Additionally, temperature-dependent optoelectronic testing shows that the device maintains a stable response up to \(140^\circ \text{C}\) and generates distinctive photocurrent at temperatures up to \(80^\circ \text{C}\), demonstrating its thermal stability. Using band structure analysis, density functional theory (DFT) calculations, and photocurrent mapping, the formation of a \(p\)-\(n\) junction is indicated, contributing to the enhanced photo response attributed to the efficient carrier separation by the built-in potential in the hetero-junction and the superior electron mobility of 2D \(\text{SnO}_2\). Our results highlight the effectiveness of integrating liquid metal-exfoliated 2D materials for enhanced photodetector performance.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Geometry-Driven Mechanical Memory in a Random Fibrous Matrix
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-24 20:00 EST
Mainak Sarkar, Christina Laukaitis, Amy Wagoner Johnson
Disordered fibrous matrices, formed by the random assembly of fibers, provide the structural framework for many biological systems and biomaterials. Applied deformation modifies the alignment and stress states of constituent fibers, tuning the nonlinear elastic response of these materials. While it is generally presumed that fibers return to their original configurations after deformation is released, except when neighboring fibers coalesce or individual fibers yield, this reversal process remains largely unexplored. The intricate geometry of these matrices leaves an incomplete understanding of whether releasing deformation fully restores the matrix or introduces new microstructural deformation mechanisms. To address this gap, we investigated the evolution of matrix microstructures during the release of an applied deformation. Numerical simulations were performed on quasi-two-dimensional matrices of random fibers under localized tension, with fibers modeled as beams in finite element analysis. After tension release, the matrix exhibited permanent mechanical remodeling, with greater remodeling occurring at higher magnitudes of applied tension, indicative of the matrix preserving its loading history as mechanical memory. This response was surprising; it occurred despite the absence of explicit plasticity mechanisms, such as activation of inter-fiber cohesion or fiber yielding. We attributed the observed remodeling to the gradient in fiber alignment that developed within the matrix microstructure under applied tension, driving the subsequent changes in matrix properties during the release of applied tension. Therefore, random fibrous matrices tend to retain mechanical memory due to their intricate geometry.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Biological Physics (physics.bio-ph)
Compaction of Granular Columns under Thermal Cycling
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-24 20:00 EST
Yuxuan Luo, Haiyang Lu, Xinyu Ai, Zelin Liu, Houfei Yuan, Zhuan Ge, Zhikun Zeng, Yujie Wang
Granular materials undergo compaction under periodic temperature fluctuations, leading to various engineering and geological phenomena from landslides to silo compaction. Although thermal effects on granular materials have been extensively studied in soil mechanics and geology, the underlying physical mechanisms remain unclear. This study investigates the compaction dynamics of granular materials subjected to thermal cycling using monodisperse glass beads and polydisperse sand packings. We demonstrate that differential thermal expansion between the container and the grains drives compaction through shear in our experimental systems. We quantify compaction dynamics using three established fitting models: Kohlrausch-Williams-Watts (KWW), double-exponential, and logarithmic functions. Our results reveal that granular materials exhibit slow relaxation processes in response to weak perturbations, displaying aging dynamics similar to those observed in glassy systems. These findings provide insights into fundamental mechanisms of granular compaction with broad implications for geological and engineering applications.
Soft Condensed Matter (cond-mat.soft)
19 pages, 6 figures
Line Edge Roughness Effects on the Thermoelectric Properties of Armchair Black Phosphorene Nanoribbons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Ebrahim Pishevar, Hossein Karamitaheri
This study delves into the thermoelectric properties of armchair black phosphorene nanoribbons while considering the presence of line edge roughness. Employing the tight-binding method in conjunction with non-equilibrium Green's function techniques and Landauer formulas, we explore the impact of various parameters on thermoelectric performance. Our findings reveal that the electrical conductivity and, consequently, the power factor exhibit an increasing trend with expanding ribbon length and width. This behavior can be attributed to heightened collision rates, particularly in narrow ribbons, induced by line edge roughness as length increases. Remarkably, the Seebeck coefficient at the Fermi energy corresponding to the maximum power factor remains nearly constant across different widths, lengths, temperatures and transport regimes. Furthermore, the thermoelectric figure of merit demonstrates a positive correlation with both ribbon length and width. In narrow widths and lengths around 1000 nm, the power factor and figure of merit exhibit an upward trend with ribbon width. However, with further increases in ribbon width, the influence of line edge roughness on thermal conductivity diminishes. Consequently, the figure of merit decreases due to the rise in thermal conductivity. Notably, the thermoelectric figure of merit is higher for short and narrow ribbons and long and wider ribbons.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Structural and optical changes induced by incorporation of antimony into InAs/GaAs(001) quantum dots
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
A. G. Taboada, A. M. Sánchez, A. M. Beltrán, M. Bozkurt, D. Alonso-Álvarez, B. Alén, A. Rivera, J. M. Ripalda, J. M. Llorens, J. Martín-Sánchez, Y. González, J. M. Ulloa, J. M. García, S. I. Molina, P. M. Koenraad
We present experimental evidence of Sb incorporation inside InAs/GaA(001) quantum dots exposed to an antimony flux immediately before capping with GaAs. The Sb composition profile inside the nanostructures as measured by cross-sectional scanning tunneling and electron transmission microscopies show two differentiated regions within the quantum dots, with an Sb rich alloy at the tip of the quantum dots. Atomic force microscopy and transmission electron microscopy micrographs show increased quantum-dot height with Sb flux exposure. The evolution of the reflection high-energy electron-diffraction pattern suggests that the increased height is due to changes in the quantum-dot capping process related to the presence of segregated Sb atoms. These structural and compositional changes result in a shift of the room-temperature photoluminescence emission from 1.26 to 1.36 microns accompanied by an order of magnitude increase in the room-temperature quantum-dot luminescence intensity.
Materials Science (cond-mat.mtrl-sci)
16 pages, 11 figures
Phys. Rev. B 82, 235316 (2010)
New process for high optical quality InAs quantum dots grown on patterned GaAs(001) substrates
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Pablo Alonso-Gonzalez, Luisa González, Yolanda González, David Fuster, Iván FernándezMartínez, Javier Martín-Sanchez, Leon Abelmann
This work presents a selective ultraviolet (UV)-ozone oxidation-chemical etching process that has been used, in combination with laser interference lithography (LIL), for the preparation of GaAs patterned substrates. Further molecular beam epitaxy (MBE) growth of InAs results in ordered InAs/GaAs quantum dot (QD) arrays with high optical quality from the first layer of QDs formed on the patterned substrate. The main result is the development of a patterning technology that allows the engineering of customized geometrical displays of QDs with the same optical quality as those formed spontaneously on flat non-patterned substrates.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 4 figures
Nanotechnology 18 355302 (2007)
Ordered InAs QDs using prepatterned substrates by monolithically integrated porous alumina
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Pablo Alonso-González, María S. Martín-González, Javier Martín-Sánchez, Yolanda González, Luisa González
In this work, we explore a method for obtaining site-controlled InAs quantum dots (QDs) on large areas of GaAs (0 0 1) pre-patterned surface. The patterning of the substrate is obtained by using a monolithically integrated nano-channel alumina (NCA) mask and transferring its self-ordering to the underlying GaAs substrate by continuing the anodization process once the GaAs surface is reached. After patterning, the GaAs substrate follows a low temperature process for surface preparation before epitaxial growth for QD formation. As a final result, we observe that the nanoholes act as preferential nucleation sites for InAs QD formation, with a filling factor close to unity, while the QD formation on the surface region between the pattern holes is completely suppressed.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 6 figures
J. Crystal Growth 294, 168-173 (2006)
Suppression of ferromagnetism in van der Waals insulator due to pressure-induced layer stacking variation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
M. Misek, U. Dutta, P. Kral, D. Hovancik, J. Kastil, K. Pokhrel, S. Ray, J. Valenta, J. Prchal, J. Kamarad, F. Borodavka, V. Eigner, M. Dusek, V. Holy, K. Carva, S. Kamba, V. Sechovsky, J. Pospisil
External pressure suppresses the ferromagnetism of localized Cr 3d electron moments in the van der Waals insulator CrBr3, which cannot be explained without considering a dramatic pressure-induced crystal or electronic structure change. We addressed this issue by conducting a parallel experimental investigation of single crystals magnetic and structural properties using magnetization, X-ray diffraction, and Raman spectroscopy measurements. Ab initio DFT calculations of electronic structure and atomistic simulations of finite-temperature magnetism supported the analysis and interpretation of experimental results. The magnetization measurements at high pressures provided the first direct experimental evidence of the pressure-induced suppression of ferromagnetism. We observed a gradual decrease of the bulk magnetic moment and Curie temperature with increasing pressure, which accelerates at pressures above 3 GPa, leading to loss of ferromagnetism at 6.5 GPa. By increasing pressure, the ambient pressure phase gradually breaks down and is accompanied by the generation of layer stacking that favor the antiferromagnetic coupling of Cr moments. As a result, the appearing antiparallel pairs of moments disturb the ferromagnetic structure and reduce the bulk magnetic moment and Curie temperature. This scenario, which is well corroborated by the results of our theoretical calculations, suggests an antiferromagnetic phase emerging with increasing pressure beyond the critical value when the new single trigonal P-3m1 phase becomes stable, characterized by the "antiferromagnetic" A-A layer stacking, becomes stable. The weak coupling between adjacent magnetic layers in van der Waals materials allows variations in layering due to sufficient external forces. We hope our comprehensive study's results can help other researchers resolve frequently appearing issues of similar origin in this class of materials.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Critical evaluations of different implementations of Edwards volume ensemble
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-24 20:00 EST
Granular systems can display reproducible microscopic distributions governed by a few macroscopic parameters, parallel to equilibrium statistical mechanics. Building on this analogy, Edwards' s pioneering framework proposes a volume ensemble of equiprobable jammed states, introducing compactivity chi as an effective temperature. Despite its promise, debates persist regarding the framework' s formulation and validity, with practical implementation often exposing inconsistencies. This study systematically examines different implementations using experimental data from spherical particle packings with varying friction coefficients, subjected to tapping and shearing. Our findings show that the heat capacity and overlapping histogram methods yield consistent Chi values. Discrepancies in other approaches, such as the free volume model, primarily stem from differing reference-state compactivities and microstate definitions, whereas the mean-field theory, which effectively accounts for mechanical stability within a geometric coordination-number phase space, is constrained by its isostatic assumption and inherent approximations. Additionally, an effective temperature Chi_f defined on Delaunay tetrahedra better describes topological excitations, but represents a quasi-equilibrium state, with true equilibrium achieved only under Chi. This study refines and expands our understanding of the Edwards volume ensemble in line with Edwards' s original ideas, highlighting the combined contributions of friction and inherently disordered packing structures.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
31 pages,8 figures
An Alternative Model For Topologically-Stable Magnetic Skyrmions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Emir Syahreza Fadhilla, M Shoufie Ukhtary, Ardian Nata Atmaja, Bobby Eka Gunara
One of the main quantities which describe the topological properties of magnetic Skyrmion is the Skyrmion number density, \(q\). In this work, we study an alternative model of a two-dimensional magnetic system where the dynamics of the spins explicitly depend on \(q\) and the Dzyaloshinskii-Moriya interaction is omitted. The Landau-Lifshitz-Gilbert dynamics is employed for the micromagnetic calculations and it is found that one of the possible static lowest energy configurations of the proposed model is a Skyrmion with a topological charge equal to one. This lowest energy configuration is stable under small linear perturbation and it is shown that the total energy of the system is bounded from below such that it is always higher than the vacuum energy, implying a topologically protected configuration. The alternative model is an effective model for Skyrmions in two-dimensional systems. We also propose that this model can be used for magnetic systems under a strong external magnetic field where the ordinary exchange interactions are much weaker than the Zeeman effect.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 4 figures, 11 pages of appendix, single column format
Two-dimensional multiferroic NbPc COF with strong magnetoelectric coupling and room-temperature ferroelectricity
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Wei Li, Dongyang Zhu, Shuai Dong, Jun-Jie Zhang
The realization of two-dimensional multiferroics offers significant potential for nanoscale device functionality. However, type-I two-dimensional multiferroics with strong magnetoelectric coupling, enabling electric field control of spin, remain scarce. In this study, using density functional theory and Monte Carlo simulations, we predict that the niobium phthalocyanine covalent organic framework (NbPc COF) monolayer exhibits type-I multiferroic behavior, with a ferroelectric transition occurring above room temperature. Remarkably, the strong magnetoelectric coupling in NbPc COF monolayer arises from the same origin of magnetism and ferroelectricity. Our findings offer flexible pathways for the design and development of organic nanoscale multiferroic devices with broad applications.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
12 pages, 5 figures
Phys. Rev. B 111, 035439 (2025)
Enhanced and Efficient Extraction of Uranyl Ions from Aqueous Waste through Graphene/CNT-PAMAM Nanocomposites
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-24 20:00 EST
Tarun Maity, Yogendra Kumar, Ashish Kumar Singha Deb, Sk Musharaf Ali, Prabal K Maiti
The increasing threat of uranium contamination to environmental and human health due to its radiotoxicity demands the development of novel and efficient adsorbents for remediation. In this study, we investigated the potential of poly(amidoamine) (PAMAM) dendrimers of generations 1 to 4 (G1 - G4) functionalized with graphene and carbon nanotubes (CNTs) as adsorbents for uranyl ion removal from aqueous solutions. By combining atomistic molecular dynamics (MD) simulations with experimental validation, we examined the influence of pH, uranyl ion concentration, and dendrimer generation on adsorption behavior. Our study revealed that uranyl ion adsorption is greater when PAMAM is grafted onto graphene/CNT than pristine PAMAM. However, PAMAM-grafted CNTs exhibit superior adsorption capacity at specific uranyl concentrations due to their curvature and abundant accessible binding sites. Higher-generation PAMAM dendrimers grafted onto graphene/CNTs exhibit greater adsorption capacity due to the increased availability of binding sites, which is consistent with experimental observations. The adsorption capability of uranyl ions in all four generations of the PAMAM dendrimer increased as the concentration of uranyl ions increased. Adsorption capacity increases with increasing uranyl ion concentration, and adsorption occurs on both PAMAM and graphene/CNT surfaces, with saturation observed at higher concentrations. This study provides insights into the adsorption mechanisms and highlights the potential of PAMAM-based nanocomposites for efficient uranyl ion extraction and environmental remediation.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Observation of Higher-order Topological Bound States in the Continuum using Ultracold Atoms
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-24 20:00 EST
Zhaoli Dong, Hang Li, Hongru Wang, Yichen Pan, Wei Yi, Bo Yan
Simulating higher-order topological materials in synthetic quantum matter is an active research frontier for its theoretical significance in fundamental physics and promising applications in quantum technologies. Here we experimentally implement two-dimensional (2D) momentum lattices with highly programmable ability using ultracold 87Rb atoms. Through precise control of experimental parameters, we simulate a 2D Su-Schrieffer-Heeger model with this technique, and observe the characteristic dynamics of corner and edge-bound states, where the corner state is identified as a higher-order topological bound state in the continuum. We further study the adiabatic preparation of the corner state by engineering evolutions with time-dependent Hamiltonians. We also demonstrate the higher-order topological phase transition by measuring both the bulk topological invariant and the topological corner state. Our new platform opens the avenue for exploring the exotic dynamics and topology in higher synthetic dimensions, making use of the rich degrees of freedom of cold atoms systems.
Quantum Gases (cond-mat.quant-gas)
7pages,4figures
Medium Temperature Phase Change Materials Thermal Characterization by the T-History Method and Differential Scanning Calorimetry
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
D. Gaona, E. Urresta, J. Martinez, G. Guerron
This paper presents a thermal characterization of salt mixtures applying the T-History Method and the Differential Scanning Calorimetry DSC techniques. By using water as a standard substance, the original T-History method was developed to analyze materials with melting points under 100 Celsius. This is the first research that proposes to replace water by glycerin to characterize medium melting temperature PCMs from 140 to 220 Celsius. Moreover, the DSC technique was used to validate and compare the results obtained with the T-history method for each mixture. For instance, the system compound of 40 KNO\(_3\) to 60 NaNO\(_3\) was studied, and the enthalpy of fusion determined by THM and DSC differs by 2.1% between each method. The results given by the two methods for all mixtures showed that both techniques are complementary and present satisfactory agreement with the specialized literature.
Materials Science (cond-mat.mtrl-sci)
11 pages, 5 figures, 2 tables, research article
Experimental Heat Transfer, 30(5), 463 to 474 (2017)
Signature of superconductivity in pressurized La4Ni3O10-x single crystals grown at ambient pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-24 20:00 EST
Feiyu Li, Yinqiao Hao, Ning Guo, Jian Zhang, Qiang Zheng, Guangtao Liu, Junjie Zhang
Nickelates have attracted enormous attention since the discovery of high-temperature superconductivity in La3Ni2O7 under high pressure. However, whether superconducting nickelate single crystals can be prepared at ambient pressure remains elusive. Here we report signature of superconductivity in pressurized La4Ni3O10-x single crystals grown from potassium carbonate flux at ambient pressure. Single crystal X-ray diffraction and scanning transmission electron microscopy investigations re-vealed high-quality single crystals with perfect stacking of trilayers. Resistivity measurements indicate that the metal-to-metal transition observed at ambient pressure was suppressed under high pressure, and a sharp drop occurred at ~30 K at 77.9 GPa, consistent with superconductivity in pressurized La4Ni3O10 single crystals grown by the floating zone method at an oxygen pressure of >18 bar. Our results not only provide an important path to prepare high-quality nickelate single crystals but also support superconductivity in nickelates under high pressure, promoting more systematic and in-depth research in this compelling field.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
3 figures
Anisotropic suppression of the phononic thermal conductivity by magnetic field in SmAlSi
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-24 20:00 EST
Mujeeb Ahmad, Md Shahin Alam, Xiaohan Yao, Fazel Tafti, Marcin Matusiak
We report the thermal and electrical conductivity data for the magnetic Weyl semimetal SmAlSi measured in a magnetic field (B) with two different orientations. In one case, B was applied perpendicular to the heat or charge current, in the other they were parallel. For both configurations, the magnetic field affects the magnetic structure identically as B is always parallel to the equivalent tetragonal axis. Our results indicate that phonon heat transport in response to the magnetic field exhibits strong anisotropy at low temperature: it appears to be independent of B in the perpendicular configuration but is strongly suppressed in the parallel configuration. Understanding this unusual behaviour can lead to designing better materials for thermoelectricity or directional heat switches.
Strongly Correlated Electrons (cond-mat.str-el)
18 pages, 5 figures
Highly Uniform Magnetic and Electronic Environment in Non-Centrosymmetric Superconductor LaRhGe\(_3\)
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-24 20:00 EST
Shunsaku Kitagawa, Hiroyasu Matsudaira, Kenji Ishida, Mohamed Oudah
We report the results of \(^{139}\)La NMR measurements in the non-centrosymmetric superconductor LaRhGe\(_3\). This material crystallizes in a tetragonal structure without inversion symmetry and exhibits type-I superconductivity below 385 mK. We observed remarkably sharp NMR signals, indicating that the magnetic and electronic properties of the sample are extremely uniform in LaRhGe\(_3\) despite the complex crystal structure. Our NMR results indicate that LaRhGe\(_3\) is a weakly correlated semimetal in the normal state.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
2 pages, 2 figures
J. Phys. Soc. Jpn. 94, 025002 (2025)
Giant end-tunneling effect in two distinct Luttinger liquids coexisting in one quantum wire
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-24 20:00 EST
Henok Weldeyesus, Pedro M.T. Vianez, Omid Sharifi Sedeh, Wooi Kiat Tan, Yiqing Jin, María Moreno, Christian P. Scheller, Jonathan P. Griffiths, Ian Farrer, David A. Ritchie, Dominik M. Zumbühl, Christopher J.B. Ford, Oleksandr Tsyplyatyev
Luttinger liquids occupy a special place in physics as the most understood case of essentially quantum many-body systems. The experimental mission of measuring its main prediction, power laws in observable quantities, has already produced a body of exponents in different semiconductor and metallic structures. Here, we combine tunneling spectroscopy with density-dependent transport measurements in the same quantum wires over more than two orders of magnitude in temperature to very low temperatures down to $$40 mK. This reveals that, when the second 1D subband becomes populated, the temperature dependence splits into two ranges with different exponents in the power-law dependence of the conductance, both dominated by the finite-size effect of the end-tunneling process. This result demonstrates the importance of measuring the Luttinger parameters as well as the number of modes independently through spectroscopy in addition to the transport exponent in the characterization of Luttinger liquids. This opens a new pathway to unambiguous interpretation of the exponents observed in quantum wires.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
27 pages, 7 figures
Mode-Shell correspondence, a unifying phase space theory in topological physics -- part II: Higher-dimensional spectral invariants
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Lucien Jezequel, Pierre Delplace
The mode-shell correspondence relates the number \(I_M\) of gapless modes in phase space to a topological \(\Ish\) defined on a close surface -- the shell -- surrounding those modes, namely \(I_M=I_S\). In part I, we introduced the mode-shell correspondence for zero-modes of chiral symmetric Hamiltonians (class AIII). In this part II, we extend the correspondence to arbitrary dimension and to both symmetry classes A and AIII. This allows us to include, in particular, \(1D\)-unidirectional edge modes of Chern insulators, massless \(2D\)-Dirac and \(3D\)-Weyl cones, within the same formalism. We provide an expression of \(I_M\) that only depends on the dimension of the dispersion relation of the gapless mode, and does not require a translation invariance. Then, we show that the topology of the shell (a circle, a sphere, a torus), that must account for the spreading of the gapless mode in phase space, yields specific expressions of the shell index. Semi-classical expressions of those shell indices are also derived and reduce to either Chern or winding numbers depending on the parity of the mode's dimension. In that way, the mode-shell correspondence provides a unified and systematic topological description of both bulk and boundary gapless modes in any dimension, and in particular includes the bulk-boundary correspondence. We illustrate the generality of the theory by analyzing several models of semimetals and insulators, both on lattices and in the continuum, and also discuss weak and higher-order topological phases within this framework. Although this paper is a continuation of Part I, the content remains sufficiently independent to be mostly read separately.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Emergent spin Hall conductivity in Tantalum-Rhenium alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Felix Janus, Jyoti Yadav, Nicolas Beermann, Wentao Zhang, Hassan A. Hafez, Dmitry Turchinovich, Sascha Preu, Markus Meinert
We investigate the spin Hall conductivity (SHC) of a composition series of a Ta-Re bcc solid solution. At approximately 60 at.% Ta the Ta-Re alloy features an SHC similar to bcc-W, while both endpoints of the compositional series have rather moderate SHC. The intermediate stoichiometries exhibit a substantial enhancement due to Fermi level tuning through the same band structure feature which gives bcc-W and \(\beta\)-W its large SHC. We provide experimental evidence for the enhancement of the SHC in the alloy via THz emission upon ultrafast laser excitation of Ta-Re/CoFeB bilayers. We demonstrate that a rigid band model derived from bcc-W and Fermi level tuning describes the experimental data with a similar accuracy as coherent potential approximation alloy calculations of the SHC.
Materials Science (cond-mat.mtrl-sci)
8 pages, 5 figures
Spin-polarized STM measurement scheme for quantum geometric tensor
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Shu-Hui Zhang, Jin Yang, Ding-Fu Shao, Jia-Ji Zhu, Wen-Long You, Wen Yang, Kai Chang
Quantum geometric tensor (QGT) reflects the geometry of the eigenstates of a system's Hamiltonian. The full characterization of QGT is essential for various quantum systems. However, it is challenging to characterize the QGT of the solid-state systems. Here we present a scheme by using spin-polarized STM to measure QGT of two-dimensional solid-state systems, in which the spin texture is extracted from geometric amplitudes of Friedel oscillations induced by the intentionally introduced magnetic impurity and then the QGT is derived from the momentum differential of spin texture. The surface states of topological insulator (TISS), as a model spin system, is promising to demonstrate the scheme. In a TI slab, the gapped TISS host finite quantum metric and Berry curvature as the symmetric real part and the antisymmetric imaginary part of QGT, respectively. Thus, a detailed calculations guide the use of the developed scheme to measure the QGT of gapped TISS with or without an external in-plane magnetic field. This study provides a feasible scheme for measuring QGT of two-dimensional solid-state systems, and hints at the great potential of the information extraction from the geometric amplitudes of STM and other measurement.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 5 figures
Experimental Realizations of Information Engines: Beyond Proof of Concept
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-24 20:00 EST
Rémi Goerlich, Laura Hoek, Omer Chor, Saar Rahav, Yael Roichman
Gathering information about a system enables greater control over it. This principle lies at the core of information engines, which use measurement-based feedback to rectify thermal noise and convert information into work. Originating from Maxwell's and Szilárd's thought experiments, the thermodynamics of information engines has steadily advanced, with recent experimental realizations both confirming established results and pushing the field forward. Coupled with technological advances and developments in nonequilibrium thermodynamics, novel implementations of information engines continue to challenge theoretical understanding. In this perspective, we discuss recent progress and highlight new opportunities, such as applying information engines to active, many-body, and inertial systems, and leveraging tools like optimal control to design their driving protocols.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
7 pages 3 figures
Room temperature observation of the anomalous in-plane Hall effect in epitaxial thin films of a Weyl ferromagnet
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Soumya Sankar, Xingkai Cheng, Tahir Murtaza, Caiyun Chen, Yuqi Qin, Xuezhao Wu, Qiming Shao, Rolf Lortz, Junwei Liu, Berthold Jäck
Topologically nontrivial electronic states can give rise to novel anomalous Hall effects. The potential appearance of these effects at room temperature holds promise for their application in magnetic sensing, spintronics, and energy harvesting technology. The anomalous in-plane Hall effect (IPHE) is predicted to arise in topological magnetic materials when an external magnetic field is applied within the sample plane. Because of stringent symmetry requirements, the conclusive detection of the anomalous IPHE induced by topological electronic states remains challenging, and the study of anomalous Hall effects is often confined to cryogenic conditions. Combining molecular beam epitaxy of the kagome metal Fe\(_3\)Sn with measurements of the electric Hall effect and theoretical calculations, we propose and experimentally demonstrate that the interplay of the kagome lattice motif with spin-orbit coupling and canted ferromagnetism with large exchange interactions gives rise to the anomalous IPHE at room temperature that is induced by topological Weyl points in the electronic band structure. Synthesizing a topological heterostructure including layers of Fe\(_3\)Sn and ferromagnetic CoFeB, we further show the enhancement of the anomalous IPHE through the magnetic stray field of the CoFeB layer. Our work establishes a design paradigm for topological magnets and heterostructures to discover and control novel anomalous Hall effects toward their use in technological applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Fragile Unconventional Magnetism in RuO\(_2\) by Proximity to Landau-Pomeranchuk Instability
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Zhuang Qian, Yudi Yang, Shi Liu, Congjun Wu
Altermagnetism has attracted considerable attention for its remarkable combination of spin-polarized band structures and zero net magnetization, making it a promising candidate for spintronics applications. We demonstrate that this magnetic phase represents a case of ``unconventional magnetism," first proposed nearly two decades ago by one of the present authors as part of a broader framework for understanding Landau-Pomeranchuk instabilities in the spin channel, driven by many-body interactions. By systematically analyzing the altermagnetism in RuO\(_2\) with first-principles calculations, we reconcile conflicting experimental and theoretical reports by attributing it to RuO\(_2\)'s proximity to a quantum phase transition. We emphasize the critical role of tuning parameters, such as the Hubbard \(U\), hole doping, and epitaxial strain, in modulating quasiparticle interactions near the Fermi surface. This work provides fresh insights into the origin and tunability of altermagnetism in RuO\(_2\), highlighting its potential as a platform for investigating quantum phase transitions and the broader realm of unconventional magnetism.
Materials Science (cond-mat.mtrl-sci)
6 pages, 3 fugures
Structural and Transport Properties of Thin InAs Layers Grown on InxAl1-xAs Metamorphic Buffers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Giulio Senesi, Katarzyna Skibinska, Alessandro Paghi, Gaurav Shukla, Francesco Giazotto, Fabio Beltram, Stefan Heun, Lucia Sorba
Indium Arsenide is a III-V semiconductor with low electron effective mass, a small band gap, strong spin-orbit coupling, and a large g-factor. These properties and its surface Fermi level pinned in the conduction band make InAs a good candidate for developing superconducting solid-state quantum devices. Here, we report the epitaxial growth of very thin InAs layers with thicknesses ranging from 12.5 nm to 500 nm grown by Molecular Beam Epitaxy on InxAl1-xAs metamorphic buffers. Differently than InAs substrates, these buffers have the advantage of being insulating at cryogenic temperatures, which allows for multiple device operations on the same wafer and thus making the approach scalable. The structural properties of the InAs layers were investigated by high-resolution X-ray diffraction, demonstrating the high crystal quality of the InAs layers. Furthermore, their transport properties, such as total and sheet carrier concentration, sheet resistance, and carrier mobility, were measured in the van der Pauw configuration at room temperature. A simple conduction model was employed to quantify the surface, bulk, and interface contributions to the overall carrier concentration and mobility.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Nanomaterials 2025, 15, 173
Emergent Polar Metal Phase in a Van der Waals Mott Magnet
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-24 20:00 EST
Shiyu Deng, Matthew J. Coak, Charles R. S. Haines, Hayrullo Hamidov, Giulio I. Lampronti, David M. Jarvis, Xiaotian Zhang, Cheng Liu, Dominik Daisenberger, Mark R. Warren, Thomas C Hansen, Stefan Klotz, Chaebin Kim, Pengtao Yang, Bosen Wang, Jinguang Cheng, Je-Geun Park, Andrew R. Wildes, Siddharth S Saxena
We report the emergence of a polar metal phase in layered van der Waals compound FePSe\(_3\). This Mott insulator with antiferromagnetic order offers a unique opportunity to fully tune an insulator into a polar metal state with pressure, without doping-induced disorder or impurities. Our synchrotron and neutron diffraction data unambiguously show a structural transition and loss of the inversion symmetry. We also observed the suppression of magnetic ordering and an insulator-to-metal transition correspondent with this structural transformation. The loss of the inversion symmetry combined with the pressure-induced metallicity in FePSe\(_3\) offers a new platform to investigate polar metallicity at accessible pressures. Moreover, the high-pressure metallic phase shows unconventional resistivity deviating from the Fermi-liquid description, close to the magnetic critical transition pressure at sufficiently low temperatures, which strongly suggests underlying quantum criticality. Our work not only explores the comprehensive temperature-pressure phase diagram of FePSe\(_3\) but also provides insights for further investigation of van der Waals strongly correlated magnetic compounds.
Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 5 figures
Topological semimetal with coexisting nodal points and nodal lines
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Bing-Bing Luo, Ming-Jian Gao, Jun-Hong An
Featuring exotic quantum transport and surface states, topological semimetals can be classified into nodal-point, nodal-line, and nodal-surface semimetals according to the degeneracy and dimensionality of their nodes. The coexistence of diverse categories of topological semimetals is of particular interest as it enables the concurrent utilization of their respective beneficial features. However, topological semimetals that possess both nodal points and nodal lines are rarely reported. Here, we propose a scheme to construct this unprecedented topological semimetal, which particularly exhibits second-order hinge Fermi arcs connecting projected nodal lines. Then, by applying periodic driving on the system, we find a hybrid-order topological semimetal with nodal points and rich nodal-lines structures and its conversion into the first-order topological semimetal, which are absent in the static system. Our results enrich the family of topological semimetals, thereby establishing a foundation for further exploration into the potential applications of these materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Scattering Insights into Shear-Induced Scission of Rod-like Micelles
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-24 20:00 EST
Guan-Rong Huang, Ryan P. Murphy, Lionel Porcar, Chi-Huan Tung, Changwoo Do, Wei-Ren Chen
Hypothesis Understanding the scission of rod-like micelles under mechanical forces is crucial for optimizing their stability and behavior in industrial applications. This study investigates how micelle length, flexibility, and external forces interact, offering insights into the design of micellar systems in processes influenced by mechanical stress. Although significant, direct experimental observations of flow-induced micellar scission using scattering techniques remain scarce. Experiments and Simulations Small angle neutron scattering (SANS) is used to explore the shear response of aqueous cetyltrimethylammonium bromide (CTAB) solutions with sodium nitrate. Rheological tests show shear thinning with no shear banding, ensuring a uniform flow field for reliable interpretation of scattering data. As shear rate increases, the scattering spectra show angular distortion, which is analyzed using spherical harmonic decomposition to characterize flow-induced scission and micelle orientation under shear. Findings Two analysis steps are used: a model-independent spectral eigendecomposition reveals a decrease in micellar length, while regression analysis quantifies the evolution of the length distribution and mean length with shear rate. Additionally, micelle alignment increases with shear, quantified by the orientational distribution function. These findings provide experimental evidence for flow-induced alignment and scission, offering a new framework for understanding shear-induced phenomena in micellar systems
Soft Condensed Matter (cond-mat.soft)
Revealing turbulent Dark Matter via merging of self-Gravitating condensates
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-24 20:00 EST
Anirudh Sivakumar, Pankaj Kumar Mishra, Ahmad A. Hujeirat, Paulsamy Muruganandam
Self-gravitating condensates have been proposed as potential candidates for modelling dark matter. In this paper, we numerically investigate the dynamics of dark matter utilizing the merging of self-gravitating condensates. We have used the Gross-Pitaevskii-Poisson model and identified distinct turbulent regimes based on the merging speed of the condensate. As a result of collision, we notice the appearance of various dark soliton-mediated instabilities that finally lead to the turbulent state characterized by Kolmogorov-like turbulence scaling ( {}^i k^{-5/3} ) in the infrared and ( {}^i k^{-3} ) in the ultraviolet regions. The compressible spectrum suggests weak-wave turbulence. The turbulent fluctuations in the condensate cease as the vortices formed via soliton decay are expelled to the condensate's periphery, manifested in the transferring of kinetic energy from incompressible and compressible flows to the quantum pressure energy. We also establish the significant role played by the self-gravitating trap in determining the distribution of compressible kinetic energy and the resulting density waves, which differ markedly from those observed in atomic condensates under harmonic confinement. Our study may offer valuable insights into the merging of binary stars and open new avenues for understanding the structure and dynamics of the dark matter through self-gravitating condensate.
Quantum Gases (cond-mat.quant-gas), General Relativity and Quantum Cosmology (gr-qc)
11 pages, 11 figures
Computational Studies of NaVTe Half Heusler Alloy for Green Energy Applications
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Sumit Kumar, Ashwani Kumar, Anupam, Shyam Lal Gupta, Diwaker
To lessen the quick depletion of fossil fuels and the resulting environmental harm, it is necessary to investigate effective and eco-friendly materials that can convert lost energy into electricity. The structural, optical, electronic, thermo-electric, and thermodynamic properties of the novel half-Heusler (HH) material NaVTe were examined in the current work using density functional theory (DFT). The Birch-Murnaghan equations of states were used to confirm the structural stability of the NaVTe HH alloy under investigation. These equations show that the compound in question has structural stability because its ground-state energy levels are negative. For spin-down configurations, NaVTe possesses an energy band gap of 3.2 eV, according to band structure and total density of state analysis. NaVTe is a material that is desirable for optoelectronic applications due to its optical features, which include maximum conductivity and absorption of electromagnetic radiation. The figure of merit and other thermodynamic and thermoelectric parameters are calculated. According to these predicted outcomes, the NaVTe HH alloy would be the ideal option for thermo-electric and renewable energy applications.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
arXiv admin note: text overlap with arXiv:2409.09735
Gauge-invariant electromagnetic responses in superconductors
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-24 20:00 EST
Sena Watanabe, Haruki Watanabe
Gauge invariance is of fundamental importance to make physically meaningful predictions. In superconductors, the use of mean-field Hamiltonians that lack \(U(1)\) symmetry often leads to gauge-dependent results. While solutions to this problem for the linear response of conventional superconductors have been well-known, a unified understanding for unconventional superconductors or nonlinear responses has not been established. This study provides the full detail of the general theoretical framework that allows us to compute responses at arbitrary orders in external fields in a gauge-invariant manner for both conventional and unconventional superconductors. Our construction generalizes the consistent fluctuations of order parameters method for full photon vertices and has a pictorial illustration using Feynman diagrams of the response kernel.
Superconductivity (cond-mat.supr-con), Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el)
22 pages, 10 figures
Large Deviations in Switching Diffusion: from Free Cumulants to Dynamical Transitions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-24 20:00 EST
Mathis Guéneau, Satya N. Majumdar, Gregory Schehr
We study the diffusion of a particle with a time-dependent diffusion constant \(D(t)\) that switches between random values drawn from a distribution \(W(D)\) at a fixed rate \(r\). Using a renewal approach, we compute exactly the moments of the position of the particle \(\langle x^{2n}(t) \rangle\) at any finite time \(t\), and for any \(W(D)\) with finite moments \(\langle D^n \rangle\). For \(t \gg 1\), we demonstrate that the cumulants \(\langle x^{2n}(t) \rangle_c\) grow linearly with \(t\) and are proportional to the free cumulants of a random variable distributed according to \(W(D)\). For specific forms of \(W(D)\), we compute the large deviations of the position of the particle, uncovering rich behaviors and dynamical transitions of the rate function \(I(y=x/t)\). Our analytical predictions are validated numerically with high precision, achieving accuracy up to \(10^{-2000}\).
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph), Probability (math.PR)
Letter: 6+2 pages and 2 figures; Supp. Mat.: 27 pages and 9 figures
Magnetic measurements under high pressure with a quantum sensor in Hexagonal Boron Nitride
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Magnetic measurements under high-pressure conditions are pivotal for the study of superconductivity and magnetic materials but remain challenging due to the micrometer-sized sample in diamond anvil cells (DAC). In this study, we propose a quantum sensing approach utilizing negatively charged boron-vacancy (V\(_B^-\)) spin defects in two-dimensional hexagonal boron nitride for high resolution magnetic measurements under pressure. The optical and spin properties of VB\(^-\) defects were systematically studied under high-pressure conditions, revealing a significant pressure-induced shift in zero-field splitting (ZFS), approximately three times larger than that of nitrogen-vacancy (NV) center. Furthermore, we demonstrate the pressure-dependent magnetic transition and variations in the Curie temperature of van der Waals ferromagnet Fe\(_3\)GeTe\(_2\) flake using V\(_B^-\) defects under pressures. Notably, the maximum operational pressure for V\(_B^-\) defects was determined to be approximately 11 GPa, attributed to a structural phase transition in hexagonal boron nitride (hBN). This work establishes the way for two-dimensional quantum sensing technologies under high-pressure environments.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Measurement of the Casimir force between superconductors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Matthijs H. J. de Jong, Evren Korkmazgil, Louise Banniard, Mika A. Sillanpää, Laure Mercier de Lépinay
The Casimir force follows from quantum fluctuations of the electromagnetic field and yields a nonlinear attractive force between closely spaced conductive objects. Its magnitude depends on the conductivity of the objects up to optical frequencies. Measuring the Casimir force in superconductors should allow to isolate frequency-specific contributions to the Casimir effect, as frequencies below the superconducting gap energy are expected to contribute differently than those above it. There is significant interest in this contribution as it is suspected to contribute to an unexplained discrepancy between predictions and measurements of the Casimir force, which questions the basic principles on which estimates of the magnitude are based. Here, we observe the Casimir force between superconducting objects for the first time, through the nonlinear dynamics it imparts to a superconducting drum resonator in a microwave optomechanical system. There is excellent agreement between the experiment and the Casimir force magnitude computed for this device across three orders of magnitude of displacement. Furthermore, the Casimir nonlinearity is intense enough that, with a modified design, this device type should operate in the single-phonon nonlinear regime. Accessing this regime has been a long-standing goal that would greatly facilitate quantum operations of mechanical resonators.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
6 pages main text (3 figures), 5 pages methods (5 figures), 12 pages supplementary information (16 figures)
Crossed Andreev reflection in collinear \(p\)-wave magnet-triplet superconductor junctions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-24 20:00 EST
Crossed Andreev reflection (CAR) is a fundamental quantum transport phenomenon with significant implications for spintronics and superconducting devices. However, its experimental detection and enhancement remain challenging. In this work, we propose a junction comprising \(p\)-wave magnets and a triplet superconductor as a promising platform to enhance CAR. The setup features a triplet superconductor sandwiched between two collinear \(p\)-wave magnets, rotated by \(180^\circ\) relative to one another, enabling precise control of transport processes. We show that CAR can dominate over electron tunneling (ET) for specific parameter regimes, such as the orientation angle of the \(p\)-wave magnets and the chemical potential. Enhanced CAR is achieved when the constant energy contours of the two spins in the \(p\)-wave magnets are well-separated. Additionally, the conductivities exhibit Fabry-Pérot-type oscillations due to interference effects, with CAR diminishing as the superconductor length exceeds the decay length of the wavefunctions. These findings highlight the potential of collinear \(p\)-wave magnet-superconductor junctions as a robust platform for the experimental study and enhancement of CAR.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
5 pages, 5 captioned figures. Comments are welcome
Ab initio modeling of single-photon detection in superconducting nanowires
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-24 20:00 EST
Alejandro Simon, Reed Foster, Mihir Sahoo, James Shi, Emma Batson, Francesca Incalza, Christoph Heil, Karl K. Berggren
Using a kinetic equation approach and Density Functional Theory, we model the nonequilibrium quasiparticle and phonon dynamics of a thin superconducting film under optical irradiation ab initio. We extend this model to develop a theory for the detection of single photons in superconducting nanowires. In doing so, we create a framework for exploring new superconducting materials for enhanced device performance beyond the state-of-the-art. Though we focus in this study on superconducting nanowire single-photon detectors, these methods are general, and they can be extended to model other superconducting devices, including transition-edge sensors, microwave resonators, and superconducting qubits. Our methods effectively integrate ab initio materials modeling with models of nonequilibrium superconductivity to perform practical modeling of superconducting devices, providing a comprehensive approach that connects fundamental theory with device-level applications.
Superconductivity (cond-mat.supr-con)
9 pages, 4 figures
Exploring the role of hydrodynamic interactions in spherically-confined drying colloidal suspensions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-24 20:00 EST
Mayukh Kundu, Kritika Kritika, Yashraj M. Wani, Arash Nikoubashman, Michael P. Howard
We study the distribution of colloidal particles confined in drying spherical droplets using both dynamic density functional theory (DDFT) and particle-based simulations. In particular, we focus on the advection-dominated regime typical of aqueous droplets drying at room temperature and systematically investigate the role of hydrodynamic interactions during this nonequilibrium process. In general, drying produces transient particle concentration gradients within the droplet in this regime, with a considerable accumulation of particles at the droplet's liquid-vapor interface. We find that these gradients become significantly larger with pairwise hydrodynamic interactions between colloidal particles instead of a free-draining hydrodynamic approximation; however, the solvent's boundary conditions at the droplet's interface (unbounded, slip, or no-slip) do not have a significant effect on the particle distribution. DDFT calculations leveraging radial symmetry of the drying droplet are in excellent agreement with particle-based simulations for free-draining hydrodynamics, but DDFT unexpectedly fails for pairwise hydrodynamic interactions after the particle concentration increases during drying, manifesting as an ejection of particles from the droplet. We hypothesize that this unphysical behavior originates from an inaccurate approximation of the two-body density correlations based on the bulk pair correlation function, which we support by measuring the confined equilibrium two-body density correlations using particle-based simulations. We identify some potential strategies for addressing this issue in DDFT.
Soft Condensed Matter (cond-mat.soft)
16 pages, 7 figures
Three-Dimensional to Layered Halide Perovskites: A Parameter-Free Hybrid Functional Method for Predicting Electronic Band Gaps
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Ibrahim Buba Garba (1), Lorenzo Trombini (1), Claudine Katan (1), Jacky Even (2), Marios Zacharias (2), Mikael Kepenekian (1), George Volonakis (1) ( (1) Univ Rennes, ENSCR, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, France, (2) Univ Rennes, INSA Rennes, CNRS, Institut FOTON - UMR 6082, Rennes, France)
Accurately predicting electronic band gaps in halide perovskites using ab initio density functional theory (DFT) is essential for their application in optoelectronic devices. Standard hybrid functionals such as HSE and PBE0 can overcome the limitations of DFT with reasonable computational cost but are known to underestimate the measured band gaps for layered halide perovskites. In this study, we assess the performance of the doubly screened dielectric-dependent hybrid (DSH) functional for predicting band gaps in three-dimensional (3D) and layered hybrid perovskites. We show that the DSH functional, which employs material-dependent mixing parameters derived from macroscopic dielectric constants, provides accurate band gap predictions for 3D halide perovskites when structural local disorder is considered. For layered hybrid perovskites, DSH functional based on average dielectric constants overestimates the band gaps. To improve the predictions and stay in a parameter-free ab initio workflow, we propose to use the calculated dielectric constant of the respective 3D perovskites. We find that the DSH functionals using the dielectric constants of the 3D perovskite accurately predict experimental gaps, with the lowest mean absolute errors compared to HSE and PBE0 for layered perovskites with various organic spacers, as well as for multilayered \(BA_2MA_{n-1}Pb_{n}I_{3n-1}\) with n = 2, 3. Notably, the HSE functional systematically underestimates the band gaps in layered perovskites. We attribute the root of this failure to the absence of non-local long-range dielectric screening, a critical factor for halide perovskites. The computational framework introduced here provides an efficient parameter-free ab initio methodology for predicting the electronic properties of 3D and layered halide perovskites and their heterostructures, aiding in developing advanced optoelectronic devices.
Materials Science (cond-mat.mtrl-sci)
Disclinations, dislocations, and emanant flux at Dirac criticality
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-24 20:00 EST
Maissam Barkeshli, Christopher Fechisin, Zohar Komargodski, Siwei Zhong
What happens when fermions hop on a lattice with crystalline defects? The answer depends on topological quantum numbers which specify the action of lattice rotations and translations in the low energy theory. One can understand the topological quantum numbers as a twist of continuum gauge fields in terms of crystalline gauge fields. We find that disclinations and dislocations -- defects of crystalline symmetries -- generally lead in the continuum to a certain ``emanant'' quantized magnetic flux. To demonstrate these facts, we study in detail tight-binding models whose low-energy descriptions are (2+1)D Dirac cones. Our map from lattice to continuum defects explains the crystalline topological response to disclinations and dislocations, and motivates the fermion crystalline equivalence principle used in the classification of crystalline topological phases. When the gap closes, the presence of emanant flux leads to pair creation from the vacuum with the particles and anti-particles swirling around the defect. We compute the associated currents and energy density using the tools of defect conformal field theory. There is a rich set of renormalization group fixed points, depending on how particles scatter from the defect. At half flux, there is a defect conformal manifold leading to a continuum of possible low-energy theories. We present extensive numerical evidence supporting the emanant magnetic flux at lattice defects and we test our map between lattice and continuum defects in detail. We also point out a no-go result, which implies that a single (2+1)D Dirac cone in symmetry class AII is incompatible with a commuting \(C_M\) rotational symmetry with \((C_M)^M = +1\).
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th)
24+15 pages, 10+10 figures
Approach to nonequilibrium: from anomalous to Brownian diffusion via non-Gaussianity
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-24 20:00 EST
I. G. Marchenko, I. I. Marchenko, J. Łuczka, J. Spiechowicz
Recent progress in experimental techniques such as single particle tracking allows to analyze both nonequilibrium properties and approach to equilibrium. There are examples showing that processes occurring at finite timescales are distinctly different than their equilibrium counterparts. In this work we analyze a similar problem of approach to nonequilibrium. We consider an archetypal model of nonequilibrium system consisting of a Brownian particle dwelling in a spatially periodic potential and driven by an external time-periodic force. We focus on a diffusion process and monitor its development in time. In the presented parameter regime the excess kurtosis measuring the Gaussianity of the particle displacement distribution evolves in a non-monotonic way: first it is negative (platykurtic form), next it becomes positive (leptokurtic form) and then decays to zero (mesokurtic form). Despite the latter fact diffusion in the long time limit is Brownian, yet non-Gaussian. Moreover, we discover a correlation between non-Gaussianity of the particle displacement distribution and transient anomalous diffusion behavior emerging for finite timescales.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Soft Condensed Matter (cond-mat.soft)
in press in Chaos
Grain-size dependence of plastic-brittle transgranular fracture
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-24 20:00 EST
Jean-Michel Scherer, Mythreyi Ramesh, Blaise Bourdin, Kaushik Bhattacharya
The role of grain size in determining fracture toughness in metals is incompletely understood with apparently contradictory experimental observations. We study this grain-size dependence computationally by building a model that combines the phase-field formulation of fracture mechanics with dislocation density-based crystal plasticity. We apply the model to cleavage fracture of body-centered cubic materials in plane strain conditions, and find non-monotonic grain-size dependence of plastic-brittle transgranular fracture. We find two mechanisms at play. The first is the nucleation of failure due to cross-slip in critically located grains within transgranular band of localized deformation, and this follows the classical Hall-Petch law that predicts a higher failure stress for smaller grains. The second is the resistance to the propagation of a mode I crack, where grain boundaries can potentially pin a crack, and this follows an inverse Hall-Petch law with higher toughness for larger grains. The result of the competition between the two mechanisms gives rise to non-monotonic behavior and reconciles the apparently contradictory experimental observations.
Materials Science (cond-mat.mtrl-sci)
Topological \(X\)-states in a quantum impurity model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-24 20:00 EST
Moallison F. Cavalcante, Marcus V. S. Bonança, Eduardo Miranda, Sebastian Deffner
Topological qubits are inherently resistant to noise and errors. However, experimental demonstrations have been elusive as their realization and control is highly complex. In the present work, we demonstrate the emergence of topological \(X\)-states in the long-time response of a locally perturbed quantum impurity model. The emergence of the double-qubit state is heralded by the lack of decay of the response function as well as the out-of-time order correlator signifying the trapping of excitations, and hence information in local edge modes.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)