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Generation of modulated magnetic structures based on cluster multipole expansion: Application to α-Mn and CoM3S6

Physical Review B 2023年第1期107卷 014407-014407页

作者： Yuki Yanagi Hiroaki Kusunose Takuya Nomoto Ryotaro Arita Michi-To Suzuki Center for Computational Materials Science Institute for Materials Research Tohoku University Sendai Miyagi 950-8577 Japan Liberal Arts and Sciences Toyama Prefectural University Imizu Toyama 939-0398 Japan Department of Physics Meiji University Kawasaki 214-8571 Japan The Institute for Solid State Physics The University of Tokyo Kashiwanoha 5-1-5 Chiba 277-8581 Japan Research Center for Advanced Science and Technology University of Tokyo Komaba Meguro-ku Tokyo 153-8904 Japan Center for Emergent Matter Science RIKEN Wako Saitama 351-0198 Japan Center for Spintronics Research Network Graduate School of Engineering Science Osaka University Toyonaka Osaka 560-8531 Japan

We present a systematic method to automatically generate symmetry-adapted magnetic structures for a given crystal structure and general propagation vector k as an efficient approach of the analysis of complex modulated magnetic structures. The method is developed as an extension of the generation scheme based on the multipole expansion, which was demonstrated only for the propagation vector k=0 [M.-T. Suzuki et al., Phys. Rev. B 99, 174407 (2019)]. The symmetry-adapted magnetic structures characterized with an ordering vector k are obtained by mapping the multipole magnetic alignments on a virtual cluster to the periodic crystal structure with the phase factor for the wave vector k. This method provides all magnetic bases compatible with irreducible representations under a k group for a given crystal structure and wave vector k. Multiple-k magnetic structures are derived from a superposition of single-k magnetic bases related to the space group symmetry. We apply the scheme to deduce the magnetic structures of α-Mn and CoM3S6 (M=Nb, Ta), in which the large anomalous Hall effect has recently been observed in antiferromagnetic phases, and identify the magnetic structures inducing anomalous Hall effect without net magnetization. The physical phenomena originating from emergent multipoles in the ordered phases are also discussed based on the Landau theory.

关键词： Anomalous Hall effect Magnetic interactions Magnetic order Order parameters Antiferromagnets Noncollinear magnets Group theory Symmetries in condensed matter

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Investigating the effects of QCD matter’s electrical conductivity on charge dependent directed flow

arXiv

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arXiv 2025年

作者： Benoit, Nicholas J. Miyoshi, Takahiro Nonaka, Chiho Takahashi, Hiroyuki R. Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima739-8511 Japan Department of Physics Nagoya University Nagoya464-8602 Japan Kobayashi Maskawa Institute Nagoya University Nagoya464-8602 Japan International Institute for Sustainability with Knotted Chiral Meta Matter Hiroshima University Higashi-Hiroshima739-8511 Japan Department of Natural Sciences Faculty of Arts and Sciences Komazawa University Tokyo154-8525 Japan

Charge dependent directed flow is an important observable of electromagnetic fields in relativistic heavy-ion collisions. We demonstrate how the difference in charge dependent directed flows between protons and antiprotons is sensitive to the resistivity, inverse of quark-gluon plasma’s electric conductivity, over different collision centralities. Our model numerically solves the 3+1D relativistic resistive magneto-hydrodynamic (RRMHD) equations, assuming the electric conductivity to be a scalar. For this work, we focus on symmetric Au + Au collisions at the top RHIC energy of √s = 200 GeV. We illustrate the time evolution of the electromagnetic fields in our model and connect that to the charge dependent directed flow results. Our results highlight the importance of modeling quark-gluon plasma’s electric conductivity for charge dependent observables in relativistic heavy-ion collisions. Copyright © 2025, The Authors. All rights reserved.

关键词： Heavy ions

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Interpretable Symbolic Regression for Data science: Analysis of the 2022 Competition

arXiv

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arXiv 2023年

作者： de Franca, F.O. Virgolin, M. Kommenda, M. Majumder, M.S. Cranmer, M. Espada, G. Ingelse, L. Fonseca, A. Landajuela, M. Petersen, B. Glatt, R. Mundhenk, N. Lee, C.S. Hochhalter, J.D. Randall, D.L. Kamienny, P. Zhang, H. Dick, G. Simon, A. Burlacu, B. Kasak, Jaan Machado, Meera Wilstrup, Casper La Cava, W.G. Federal University of ABC Santo Andre Brazil Evolutionary Intelligence Group Centrum Wiskunde & Informatica Science Park 123 Amsterdam Netherlands Computational Health Informatics Program Boston Children's Hospital Harvard Medical School Boston United States University of Applied Sciences Upper Austria Hagenberg Austria Center for Computational Astrophysics Flatiron Institute Department of Astrophysical Sciences Princeton University United States LASIGE Faculdade de Ciências Universidade de Lisboa Lisboa Portugal Computational Engineering Division Lawrence Livermore National Laboratory Livermore United States University of Utah Department of Mechanical Engineering Utah United States Meta FAIR France Victoria University of Wellington School of Engineering and Computer Science New Zealand University of otago Department of Information Science New Zealand Institut für Angewandte Physik Universität Tübingen Max Planck Institute for Intelligent Systems Tübingen Germany Abzu AI Orient Plads 1 Nordhavn 2150 Denmark

Symbolic regression searches for analytic expressions that accurately describe studied phenomena. The main attraction of this approach is that it returns an interpretable model that can be insightful to users. Historically, the majority of algorithms for symbolic regression have been based on evolutionary algorithms. However, there has been a recent surge of new proposals that instead utilize approaches such as enumeration algorithms, mixed linear integer programming, neural networks, and Bayesian optimization. In order to assess how well these new approaches behave on a set of common challenges often faced in real-world data, we hosted a competition at the 2022 Genetic and Evolutionary Computation Conference consisting of different synthetic and real-world datasets which were blind to entrants. For the real-world track, we assessed interpretability in a realistic way by using a domain expert to judge the trustworthiness of candidate models. We present an in-depth analysis of the results obtained in this competition, discuss current challenges of symbolic regression algorithms and highlight possible improvements for future competitions. Copyright © 2023, The Authors. All rights reserved.

关键词： Machine learning

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Exploring the magnetic properties of individual barcode nanowires using wide-field diamond microscopy

arXiv

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arXiv 2023年

作者： Yoon, Jungbae Moon, Jun Hwan Jeong, Jugyeong Kim, Yu Jin Kim, Kihwan Kang, Hee Seong Jeon, Yoo Sang Oh, Eunsoo Lee, Sun Hwa Han, Kihoon Lee, Dongmin Lee, Chul-Ho Kim, Young Keun Lee, Donghun Department of Physics Korea University Seoul Korea Republic of Department of Materials Science and Engineering Korea University Seoul Korea Republic of Institute for High Technology Materials and Devices Korea University Seoul Korea Republic of KU-KIST Graduate School of Converging Science and Technology Korea University Seoul Korea Republic of Center for Hydrogen∙Fuel Cell Research Korea Institute of Science and Technology Seoul Korea Republic of Ulsan44919 Korea Republic of BK21 Graduate Program Department of Biomedical Sciences Korea University College of Medicine Seoul Korea Republic of Department of Neuroscience Korea University College of Medicine Seoul Korea Republic of Department of Anatomy Korea University College of Medicine Seoul Korea Republic of

Barcode magnetic nanowires typically comprise a multilayer magnetic structure in a single body with more than one segment type. Interestingly, owing to selective functionalization and novel interactions between the layers, barcode magnetic nanowires have attracted significant attention, particularly in the field of bioengineering. However, an analysis of their magnetic properties at the individual nanowire level remains challenging. With this background, herein, we investigated the characterization of magnetic nanowires at room temperature under ambient conditions based on magnetic images obtained via wide-field quantum microscopy with nitrogen-vacancy centers in diamond. Consequently, we could extract critical magnetic properties, such as the saturation magnetization and coercivity, of single nanowires by comparing the experimental results with those of micromagnetic simulations. This study opens up the possibility for a versatile characterization method suited to individual magnetic nanowires. © 2023, CC BY.

关键词： Diamonds

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Structural Properties of Hyperuniform Networks

arXiv

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arXiv 2024年

作者： Newby, Eli Shi, Wenlong Jiao, Yang Albert, Reka Torquato, Salvatore Department of Physics Pennsylvania State University University ParkPA16802 United States Materials Science and Engineering Arizona State University TempeAZ85287 United States Department of Physics Arizona State University TempeAZ85287 United States Department of Chemistry Princeton University PrincetonNJ08544 United States Department of Physics Princeton University PrincetonNJ08544 United States Princeton Institute of Materials Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

Disordered hyperuniform many-particle systems are recently discovered exotic states of matter, characterized by a complete suppression of normalized infinite-wavelength density fluctuations, as in perfect crystals, and lack of conventional long-range order, as in liquids and glasses. In this work, we begin a program to quantify the structural properties of nonhyperuniform and hyperuniform networks. In particular, large two-dimensional (2D) Voronoi networks (graphs) containing approximately 10,000 nodes are created from a variety of different point configurations, including the antihyperuniform hyperplane intersection process (HIP), nonhyperuniform Poisson process, nonhyperuniform random sequential addition (RSA) saturated packing, and both non-stealthy and stealthy hyperuniform point processes. We carry out an extensive study of the Voronoi-cell area distribution of each of the networks through determining multiple metrics that characterize the distribution, including their higher-cumulants (i.e., skewness 1 and excess kurtosis 2). We show that the HIP distribution is far from Gaussian, as evidenced by a high skewness (γ1 = 3.16) and large positive excess kurtosis (γ2 = 16.2). The Poisson (with γ1 = 1.07 and γ2 = 1.79) and non-stealthy hyperuniform (with γ1 = 0.257 and γ2 = 0.0217) distributions are Gaussian-like distributions, since they exhibit a small but positive skewness and excess kurtosis. The RSA (with γ1 = 0.450 and γ2 = -0.0384) and the highest stealthy hyperuniform distributions (with γ1 = 0.0272 and γ2 = -0.0626) are also non-Gaussian because of their low skewness and negative excess kurtosis, which is diametrically opposite non-Gaussian behavior of the HIP. The fact that the cell-area distributions of large, finite-sized RSA and stealthy hyperuniform networks (e.g., with N ≈ 10, 000 nodes) are narrower, have larger peaks, and smaller tails than a Gaussian distribution implies that in the thermodynamic limit the distributions should exhibit compact suppo

关键词： Gaussian distribution

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Phase-engineered heterostructures of Mo2C by plasma-assisted selenization and sulfurization processes toward excellent hydrogen evolution reaction

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Nano Energy 2024年 122卷

作者： Kimbulapitiya, K.M.M.D.K. Rehman, Bushra Wani, Sumayah Shakil Chen, Chieh-Ting Cyu, Ruei-Hong Manikandan, Arumugam Date, Manisha Kondiba Peng, Yu-Ren Kumara, R.J.G.L.R. Chuang, Feng-Chuan Chueh, Yu-Lun Department of Physics National Sun Yat-sen University Kaohsiung80424 Taiwan Department of Materials Science and Engineering National Tsing-Hua University Hsinchu Taiwan College of Semiconductor Research National Tsing-Hua University Hsinchu30013 Taiwan Center for Nanotechnology Materials Science and Microsystem National Tsing-Hua University Hsinchu Taiwan Ph.D. Program in Prospective Functional Materials Industry National Tsing Hua University Hsinchu30013 Taiwan Physics Division National Center for Theoretical Sciences Hsinchu30013 Taiwan Center for Theoretical and Computational Physics National Sun Yat-Sen University Kaohsiung80424 Taiwan Department of Physics National Tsing Hua University Hsinchu30013 Taiwan

Due to the outstanding semiconducting and metallic properties, 2D materials such as Transition Metal dichalcogenides (TMDs) and Transition Metal Carbides (TMCs) appear to be promising candidate for Nano-scale electronics devices. Among them, 2D - Mo2C (Molybdenum carbide) has attracted attention as a new member of the MXene group, owing to its potential applications for superconductors, electronics devices, and catalysts for Hydrogen evolution Reactions (HER). Structural modification toward the creation of novel heterostructures with phase engineering opens new pathways for different applications. Herein, we prepared a large area Mo2C film by chemical vapor deposition method. The upper region of Mo2C layers can be oxidized to create Mo2C/MoOx heterostructures. Furthermore, those oxide layers were further transformed into MoSe2 and MoS2 by plasma-assisted selenization and sulfurization processes at different temperatures with a fixed plasma power of 150 W. The heterostructures demonstrated outstanding electrocatalytic activity for HER due to an existed metallic phase and active sites present after plasma-assisted selenization and sulfurization processes at the low temperature. The performance of the HER decreases at high temperatures owing to their semiconducting phase. The pristine Mo2C showed a Tafel slope of 72 mV dec−1 and an overpotential of 276 mV at 10 mA/cm2, while the Mo2C/MoSe2 heterostructure synthesized at 350 °C350 °exhibited an improved Tafel slope of 66 mV dec−1 and overpotential of 257 mV at 10 mA/ cm2. Additionally, the Mo2C/MoS2 heterostructure prepared at 350 °C also demonstrated a 263 mV improvement in overpotential at 10 mA/cm2. All the heterostructures showed excellent stability over a period of 10 h except Mo2C/MoOx. This work opens new strategies to fabricate high-quality MXene and TMDs heterostructures with metal-semiconductor interface. © 2024

关键词： Molybdenum compounds

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No external load measurement strategy for micro thermoelectric generator based on high-performance Si_(1-x-y)Ge_(x)Sn_(y) film

引用

Journal of Materiomics 2021年第4期7卷 665-671页

作者： Ying Peng Sijing Zhu Huajun Lai Jie Gao Masashi Kurosawa Osamu Nakatsuka Sakae Tanemura Biaolin Peng Lei Miao Guangxi Key Laboratory of Information Material School of Material Science and EngineeringGuilin University of Electronic TechnologyGuilin541004China Department of Materials Physics Graduate School of EngineeringNagoya UniversityNagoya464-8603Japan PRESTO Japan Science and Technology Agency4-1-8HonchoKawaguchiSaitama332-0012Japan Institute of Materials and Systems for Sustainability Nagoya UniversityNagoya464-8601Japan Japan Fine Ceramics Center 2-4-1 MutsunoAtsuta-kuNagoya456-8587Japan Center on Nanoenergy Research Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured MaterialsGuangxi Key Laboratory for Relativity AstrophysicsNanning530004China Department of Materials Science and Engineering SIT Research LaboratoriesInnovative Global ProgramFaculty of EngineeringShibaura Institute of TechnologyTokyo135-8548Japan

In this study,a micro in-plane p-type thermoelectric generator(TEG),which consists of thin-film Si_(1-x-y)Ge_(x)Sn_(y) ternary alloy semiconductor on insulator,is developed to make efficient use of waste heat such as human body.A power factor value as high as 1095 mWm^(-1) K^(-2) had been achieved using Bion implanted and short-term rapid thermal annealing(RTA)*** addition,a measuring scheme for micro TEG without external load resistance was *** one measuring session,multiple parameters can be *** micro single-arm TEG prepared by semiconductor process can output 0.29 nW power at a temperature difference of 15 K,and a cross-sectional power density has reached up to 0.58 mW/cm^(2),which is a superior value for wearable *** findings of this study have important reference value for wearable device performance improvement and output power measuring of micro TEG.

关键词： Si_(1-x-y)Ge_(x)Sn_(y) film P-type TEG No external load measurement Ambient power density

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Terahertz Time-Domain Spectroscopy for Probing DC Conductivity of Single-Layer Graphene

Terahertz Time-Domain Spectroscopy for Probing DC Conductivi...

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Western New York Image Processing Workshop (WNYIPW)

作者： Debamitra Chakraborty Declan Walden Jing Cheng Julia Wallace Kiryl A. Niherysh Andrei V. Felsharuk Donats Erts Ivan Komissarov Roman Sobolewski Materials Science Graduate Program University of Rochester Rochester New York USA Laboratory for Laser Energetics Rochester New York USA Department of Physics and Astronomy University of Rochester Rochester New York USA Department of Biomedical Engineering University of Rochester Rochester New York USA Institute of Chemical Physics University of Latvia Riga Latvia Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg Sweden Department of Electrical and Computer Engineering University of Rochester Rochester New York USA

We report preliminary results of extracting electrical parameters like DC conductivity, mobility, and carrier concentration of single-layer graphene using Terahertz time-domain spectroscopy (THz-TDS) in transmission geometry. We utilize a simple Drude model and its extension, the Drude-Smith model, capable of accommodating charge carrier scattering by optical and acoustic phonons to describe the complex conductivity in graphene. We observed that a significant area of the sample scanned followed the Drude-Smith behavior, while at a few locations, the simple Drude behavior prevailed. We identified possible reasons that might contribute to this observation, like defects, the presence of polymer residue on the sample, or the sample strain. This research sheds new light on our understanding of graphene's electrical properties and lays the foundation for future investigations addressing defects and contaminants in graphene samples.

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Randomizing hypergraphs preserving degree correlation and local clustering

arXiv

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arXiv 2021年

作者： Nakajima, Kazuki Shudo, Kazuyuki Masuda, Naoki Department of Mathematical and Computing Science Tokyo Institute of Technology Japan Department of Mathematics State University of New York Buffalo United States Computational and Data-Enabled Science and Engineering Program State University of New York Buffalo United States Faculty of Science and Engineering Waseda University Japan

Many complex systems involve direct interactions among more than two entities and can be represented by hypergraphs, in which hyperedges encode higher-order interactions among an arbitrary number of nodes. To analyze structures and dynamics of given hypergraphs, a solid practice is to compare them with those for randomized hypergraphs that preserve some specific properties of the original hypergraphs. In the present study, we propose a family of such reference models for hypergraphs, called the hyper dk-series, by extending the so-called dk-series for dyadic networks to the case of hypergraphs. The hyper dk-series preserves up to the individual node’s degree, node’s degree correlation, node’s redundancy coefficient, and/or the hyperedge’s size depending on the parameter values. Furthermore, we numerically find that higher-order hyper dk-series more accurately preserves the shortest path length and degree distribution of the one-mode projection of the original hypergraph, which the method does not intend to preserve. We also apply the hyper dk-series to numerical simulations of epidemic spreading and evolutionary game dynamics on empirical social hypergraphs. We find that the hyperedge’s size affects these dynamics more than any of the node’s properties and that the node’s degree correlation and redundancy in the empirical hypergraphs promote cooperation. Copyright © 2021, The Authors. All rights reserved.

关键词： Redundancy

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Designing the pressure-dependent shear modulus using tessellated granular metamaterials

arXiv

引用

arXiv 2023年

作者： Zhang, Jerry Wang, Dong Jin, Weiwei Xia, Annie Pashine, Nidhi Kramer-Bottiglio, Rebecca Shattuck, Mark D. O’Hern, Corey S. Department of Mechanical Engineering & Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States

Jammed packings of granular materials display complex mechanical response. For example, the ensemble-averaged shear modulus 〈G〉 increases as a power-law in pressure p for static packings of soft spherical particles that can rearrange during compression. We seek to design granular materials with shear moduli that can either increase or decrease with pressure without particle rearrangements even in the large-system limit. To do this, we construct tessellated granular metamaterials by joining multiple particle-filled cells together. We focus on cells that contain a small number of bidisperse disks in two dimensions. We first study the mechanical properties of individual disk-filled cells with three types of boundaries: periodic boundary conditions (PBC), fixed-length walls (FXW), and flexible walls (FLW). Hypostatic jammed packings are found for cells with FLW, but not in cells with PBC and FXW, and they are stabilized by quartic modes of the dynamical matrix. The shear modulus of a single cell depends linearly on p. We find that the slope of the shear modulus with pressure, λc c > 0, as well as λc © 2023, CC BY.

关键词： Elastic moduli

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