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Nonlinear and Nonreciprocal Transport Effects in Untwinned Thin Films of Ferromagnetic Weyl Metal SrRuO3

Physical Review X 2024年第1期14卷 011022-011022页

作者： Uddipta Kar Elisha Cho-Hao Lu Akhilesh Kr. Singh P. V. Sreenivasa Reddy Youngjoon Han Xinwei Li Cheng-Tung Cheng Song Yang Chun-Yen Lin I-Chun Cheng Chia-Hung Hsu David Hsieh Wei-Cheng Lee Guang-Yu Guo Wei-Li Lee Institute of Physics Academia Sinica Nankang Taipei 11529 Taiwan Nano Science and Technology Taiwan International Graduate Program Academia Sinica and National Taiwan University Taipei Taiwan Department of Physics National Taiwan University Taipei 10617 Taiwan Department of Physics California Institute of Technology Pasadena California 91125 USA Scientific Research Division National Synchrotron Radiation Research Center Hsinchu 30076 Taiwan Graduate Institute of Photonics and Optoelectronics National Taiwan University Taipei Taiwan Department of Physics Applied Physics and Astronomy Binghamton University Binghamton New York 13902 USA Physics Division National Center for Theoretical Sciences Taipei 10617 Taiwan

The identification of distinct charge transport features, deriving from nontrivial bulk band and surface states, has been a challenging subject in the field of topological systems. In topological Dirac and Weyl semimetals, nontrivial conical bands with Fermi-arc surface states give rise to negative longitudinal magnetoresistance due to chiral anomaly effect and unusual thickness dependent quantum oscillation from Weyl-orbit effect, which were demonstrated recently in experiments. In this work, we report the experimental observations of large nonlinear and nonreciprocal transport effects for both longitudinal and transverse channels in an untwinned Weyl metal of SrRuO3 thin film grown on a SrTiO3 substrate. From rigorous measurements with bias current applied along various directions with respect to the crystalline principal axes, the magnitude of nonlinear Hall signals from the transverse channel exhibits a simple sinα dependence at low temperatures, where α is the angle between bias current direction and orthorhombic [001]o, reaching a maximum when current is along orthorhombic [11¯0]o. On the contrary, the magnitude of nonlinear and nonreciprocal signals in the longitudinal channel attains a maximum for bias current along [001]o, and it vanishes for bias current along [11¯0]o. The observed α-dependent nonlinear and nonreciprocal signals in longitudinal and transverse channels reveal a magnetic Weyl phase with an effective Berry curvature dipole along [11¯0]o from surface states, accompanied by 1D chiral edge modes along [001]o.

关键词： Electrical conductivity Hall effect Quantum transport Topological materials Topological phases of matter Transport phenomena Magnetic thin films Thin films Weyl semimetal Boltzmann theory Continuous symmetries in condensed matter Epitaxy Film deposition Hall bar Methods in transport Resistivity measurements Symmetries in condensed matter Transport techniques

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Partial observation can induce mechanistic mismatches in data-constrained models of neural dynamics 24

Partial observation can induce mechanistic mismatches in dat...

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Proceedings of the 38th International Conference on Neural Information Processing Systems

作者： William Qian Jacob A. Zavatone-Veth Benjamin S. Ruben Cengiz Pehlevan Biophysics Graduate Program and Kempner Institute for the Study of Natural and Artificial Intelligence Harvard University Cambridge MA John A. Paulson School of Engineering and Applied Sciences and Center for Brain Science Harvard University and Department of Physics Harvard University Cambridge MA Biophysics Graduate Program Harvard University Cambridge MA Kempner Institute for the Study of Natural and Artificial Intelligence and John A. Paulson School of Engineering and Applied Sciences and Center for Brain Science Harvard University Cambridge MA

ISBN: (纸本)9798331314385

One of the central goals of neuroscience is to gain a mechanistic understanding of how the dynamics of neural circuits give rise to their observed function. A popular approach towards this end is to train recurrent neural networks (RNNs) to reproduce experimental recordings of neural activity. These trained RNNs are then treated as surrogate models of biological neural circuits, whose properties can be dissected via dynamical systems analysis. How reliable are the mechanistic insights derived from this procedure? While recent advances in population-level recording technologies have allowed simultaneous recording of up to tens of thousands of neurons, this represents only a tiny fraction of most cortical circuits. Here we show that observing only a subset of neurons in a circuit can create mechanistic mismatches between a simulated teacher network and a data-constrained student, even when the two networks have matching single-unit dynamics. In particular, partial observation of models of low-dimensional cortical dynamics based on functionally feedforward or low-rank connectivity can lead to surrogate models with spurious attractor structure. Our results illustrate the challenges inherent in accurately uncovering neural mechanisms from single-trial data, and suggest the need for new methods of validating data-constrained models for neural dynamics.

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Super-Mossian Dielectrics for Nanophotonics

Super-Mossian Dielectrics for Nanophotonics

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Conference on Lasers and Electro-Optics (CLEO)

作者： Xielin Wang Chloe F. Doiron Zhichao Li Jacob B. Khurgin Gururaj V. Naik Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston TX Department of Electrical and Computer Engineering Johns Hopkins University Baltimore MD Department of Electrical and Computer Engineering Rice University Houston TX

Searching for high-index dielectrics, we identify materials that break the index upper bound set by Moss’ rule. We highlight the promise of such super-Mossian materials by demonstrating nanophotonic devices made of F... 详细信息

ISBN: (纸本)9781957171258

关键词： Fourier transform infrared spectroscopy Nanophotonics Optical constants Optical materials Refractive index Whispering gallery modes

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Deep-Strong Coupling between Cavity Photons and Terahertz TO Phonons in PbTe

Deep-Strong Coupling between Cavity Photons and Terahertz TO...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Baydin, Andrey Manjappa, Manukumara Mishra, Sobhan Subhra Xu, Hongjing Tay, Fuyang Kim, Dasom Hernandez, Felix G.G. Rappl, Paulo H.O. Abramof, Eduardo Singh, Ranjan Kono, Junichiro Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Smalley-Curl Institute Rice University HoustonTX77005 United States Instrumentation and Applied Physics Department Indian Institute of Science Bangalore560012 India Center for Disruptive Photonic Technologies The Photonics Institute Nanyang Technological University 639798 Singapore Department of Physics and Astronomy Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Instituto de Física Universidade de Sao Paulo SP Sao Paulo05508-090 Brazil Laboratorio Associado de Sensores e Materiais Instituto Nacional de Pesquisas Espaciais SP Sao Jose dos Campos12201-970 Brazil Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 637371 Singapore Department of Material Science and NanoEngineering Rice University HoustonTX77005 United States

We have investigated the resonant coupling of photons with TO phonons in lead telluride in small-mode-volume terahertz cavities, observing a giant vacuum Rabi splitting on the order of the bare cavity-phonon frequency... 详细信息

ISBN: (纸本)9781957171258

关键词： Photons

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Structural, magnetic, and electronic properties of a GdAsSe single crystal: Experimental and theoretical studies

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Physical Review B 2024年第18期109卷 184420-184420页

作者： R. Kalaivanan Balaji Venkatesan B. Dundi Sri Chandana Rajesh Kumar Ulaganathan G. Senthil Murugan K. Moovendaran Joydev Khatua Li-Hsin Su W. Zhou Xiaofeng Xu Chia-Seng Chang Tien-Ming Chuang Yoshiyuki Iizuka I. Panneer Muthuselvam Horng-Tay Jeng Kwang-Yong Choi Raman Sankar Institute of Physics Academia Sinica Taipei 10617 Taiwan Department of Physics National Taiwan University Taipei 10617 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica and National Taiwan University Taipei 11529 Taiwan Department of Physics School of Basic and Applied Sciences Central University of Tamil Nadu Neelakudi Thiruvarur 610005 Tamil Nadu India Department of Physics Sungkyunkwan University Suwon 16419 Republic of Korea Department of Physics National Tsing Hua University Hsinchu 30013 Taiwan Department of Electro Physics National Yang Ming Chiao Tung University Hsinchu 300093 Taiwan School of Electronic and Information Engineering Changshu Institute of Technology Changshu 215500 China Department of Applied Physics Zhejiang University of Technology Hangzhou 310023 China Institute of Earth Sciences Academia Sinica Taipei 10617 Taiwan Department of Physics (MMV) Banaras Hindu University Varanasi 221005 Uttar Pradesh India Physics Division National Center for Theoretical Sciences Taipei 10617 Taiwan

We report high-quality single-crystal growth, x-ray diffraction, magnetic susceptibility [χ(T,H)], magnetization [M(H)], heat capacity [CP(T,H)], electrical resistivity [ρ(T,H)], and electron spin resonance (ESR) measurements of GdAsSe as functions of temperature and magnetic field. We identify an antiferromagnetic phase transition at TN∼11.9±0.2 K and construct magnetic phase diagrams for H||ab and H||c axes based on the χ(T,H) and CP(T,H) data. Isothermal M(H) curves along the H||ab direction at 3 K exhibit a field-induced spin orientation at HC∼3.78T. Both M(H) and χ(T,H) indicate an easy-plane-type anisotropy. The Curie-Weiss analysis of the high-temperature paramagnetic χ(T) yields a negative Weiss temperature, suggesting dominant antiferromagnetic interactions between the Gd ions. Magnetic entropy reaches 83% of R ln8 at TN. The presence of residual entropy above TN and the persistence of ESR critical broadening up to ∼3TN alludes to a degree of magnetic frustration in the studied material. The ρ(T) data above TN is well fitted to the Bloch-Grüneisen theory for metals. Further, density functional theory calculations reveal an antiferromagnetic ground state where the Gd atoms are coupled ferromagnetically in the ab plane and antiferromagnetically along the c axis.

关键词： Magnetic anisotropy Magnetic coupling Magnetic interactions Magnetic order Magnetism

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Assessment of scoring functions for computational models of protein-protein interfaces

arXiv

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arXiv 2024年

作者： Sumner, Jacob Meng, Grace Brandt, Naomi Grigas, Alex T. Córdoba, Andrés Shattuck, Mark D. O’Hern, Corey S. Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Chemistry Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States Department of Chemistry Duke University DurhamNC27708 United States Department of Physics Duke University DurhamNC27708 United States Benjamin Levich Institute Physics Department City College of New York New YorkNY10031 United States Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States

A goal of computational studies of protein-protein interfaces (PPIs) is to predict the binding site between two monomers that form a heterodimer. The simplest version of this problem is to rigidly re-dock the bound forms of the monomers, which involves generating computational models of the heterodimer and then scoring them to determine the most native-like models. Scoring functions have been assessed previously using rank- and classification-based metrics, however, these methods are sensitive to the number and quality of models in the scoring function training set. We assess the accuracy of seven PPI scoring functions by comparing their scores to a measure of structural similarity to the x-ray crystal structure (i.e. the DockQ score) for a non-redundant set of heterodimers from the Protein Data Bank. For each heterodimer, we generate re-docked models uniformly sampled over DockQ and calculate the Spearman correlation between the PPI scores and DockQ. For some targets, the scores and DockQ are highly correlated;however, for many targets, there are weak correlations. Several physical features can explain the difference between difficult- and easy-to-score targets. For example, strong correlations exist between the score and DockQ for targets with highly intertwined monomers and many interface contacts. We also develop a new score based on only three physical features that matches or exceeds the performance of current PPI scoring functions. These results emphasize that PPI prediction can be improved by focusing on correlations between the PPI score and DockQ and incorporating more discriminating physical features into PPI scoring functions. © 2024, CC BY.

关键词： Monomers

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Partial observation can induce mechanistic mismatches in data-constrained models of neural dynamics 38

Partial observation can induce mechanistic mismatches in dat...

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38th Conference on Neural Information Processing Systems, NeurIPS 2024

作者： Qian, William Zavatone-Veth, Jacob A. Ruben, Benjamin S. Pehlevan, Cengiz Biophysics Graduate Program Harvard University CambridgeMA02138 United States Kempner Institute for the Study of Natural and Artificial Intelligence Harvard University CambridgeMA02138 United States John A. Paulson School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States Center for Brain Science Harvard University CambridgeMA02138 United States Department of Physics Harvard University CambridgeMA02138 United States

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Using 4D-STEM to Map 3D Morphologies of 2D Materials

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Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada 2023年第1期29卷 262-263页

作者： Mireles, Adan Shi, Chuqiao Park, Jeongwon Shin, Bongki Sung, Suk Hyun Ophus, Colin Hovden, Robert Kang, Kibum Han, Yimo Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston TX United States Department of Materials Science and NanoEngineering Rice University Houston TX United States Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon South Korea Department of Materials Science and Engineering University of Michigan Ann Arbor MI United States National Center for Electron Microscopy Molecular Foundry Lawrence Berkeley National Laboratory Berkeley CA United States

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Mechanism of intermetallic charge transfer and bond disproportionation in BiNiO3 and PbNiO3 revealed by hard x-ray photoemission spectroscopy

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Physical Review B 2024年第20期109卷 205131-205131页

作者： Tatsuya Yamaguchi Mizuki Furo Yuki Sakai Takumi Nishikubo Hajime Hojo Masaki Azuma Kengo Oka Daisuke Mori Yoshiyuki Inaguma Masaichiro Mizumaki Kento Yamamoto Jan Kuneš Takashi Mizokawa Atsushi Hariki Department of Physics and Electronics Graduate School of Engineering Osaka Metropolitan University 1-1 Gakuen-cho Nakaku Sakai Osaka 599-8531 Japan Kanagawa Institute of Industrial Science and Technology (KISTEC) Ebina 243-0435 Japan Materials and Structures Laboratory Institute of Innovative Research Tokyo Institute of Technology 4259 Nagatsuta Midori Yokohama 226-8501 Japan Department of Advanced Materials Science and Engineering Faculty of Engineering Sciences Kyushu University 6-1 Kasuga-koen Kasuga Fukuoka 816-8580 Japan Department of Applied Chemistry Faculty of Science and Engineering Chuo University 1-13-27 Kasuga Bunkyo-ku Tokyo 112-8551 Japan Department of Applied Chemistry Faculty of Science and Engineering Kindai University 3-4-1 Kowakae Higashi-Osaka Osaka 577-8502 Japan Department of Chemistry Faculty of Science Gakushuin University 1-5-1 Mejiro Toshima-ku Tokyo 171-8588 Japan Department of Applied Chemistry Graduate School of Engineering Mie University Tsu Mie 514-8507 Japan Institute of Industrial Nanomaterials Kumamoto University 2-39-1 Kurokami Chuo-ku Kumamoto 860-8555 Japan Department of Applied Physics Waseda University 3-4-1 Okubo Shinjuku-ku Tokyo 169-8555 Japan Institute of Solid State Physics TU Wien 1040 Vienna Austria Department of Condensed Matter Physics Faculty of Science Masaryk University Kotlářská 2 611 37 Brno Czechia

Perovskites with Bi or Pb on the A site host a number of interesting and yet to be understood phenomena such as negative thermal expansion in BiNiO3. We employ hard x-ray photoemission spectroscopy of Ni 2p core level as well as valence band to probe the electronic structure of BiNiO3 and PbNiO3. The experimental results supported by theoretical calculations using dynamical mean-field theory reveal essentially identical electronic structure of the Ni–O subsystem typical of Ni2+ charge-transfer insulators. The two materials are distinguished by filling of the Bi(Pb)–O antibonding states in the vicinity of the Fermi level, which is responsible for the Bi disproportionation in BiNiO3 at ambient pressure and absence of similar behavior in PbNiO3. The present experiments provide evidence for this conclusion by revealing the presence/absence of Bi/Pb 6s states at the top of the valence band in the two materials.

关键词： Metal-insulator transition Perovskites Transition metal oxides Density functional theory Dynamical mean field theory Hard x-ray photoelectron spectroscopy Photoemission spectroscopy

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Efficient general waveform catching by a cavity at an absorbing exceptional point

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Physical Review A 2024年第4期109卷 L041502-L041502页

作者： Asaf Farhi Wei Dai Seunghwi Kim Andrea Alù Douglas Stone Department of Applied Physics Yale University New Haven Connecticut 06520 USA Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Physics Program Graduate Center City University of New York New York New York 10016 USA Yale Quantum Institute Yale University New Haven Connecticut 06520 USA

We study a system tuned to an absorbing exceptional point and explore its use to efficiently receive and store an incoming wave with an envelope different from the absorbing-eigenmode envelope. Specifically, while absorbing states of lossless resonators have an exponentially increasing envelope, we focus on capturing naturally emitted waves with an exponentially decreasing envelope. We find that, when tuning a cavity to an nth-order absorbing exceptional point (EP), n+1 temporal orders of any incoming waveform can be perfectly captured, leading to significantly less scattering and increasing the overall absorption efficiency for general waveforms. We present an approach to tune a cavity to an EP and demonstrate less scattering by an order of magnitude for a decaying incoming waveform. Our results may be used for efficient passive state transfer and detection of spontaneous emission.

关键词： Optical transient phenomena Scattering theory Spontaneous emission Atomic systems Molecules Non-Hermitian systems Quantum cavities Trapped ions

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