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In Situ Electric-Field Control of THz Nonreciprocal Directional Dichroism in the Multiferroic Ba2CoGe2O7

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Physical Review Letters 2021年第15期127卷 157201-157201页

作者： J. Vít J. Viirok L. Peedu T. Rõõm U. Nagel V. Kocsis Y. Tokunaga Y. Taguchi Y. Tokura I. Kézsmárki P. Balla K. Penc J. Romhányi S. Bordács Department of Physics Budapest University of Technology and Economics 1111 Budapest Hungary Institute of Physics ASCR Na Slovance 2 182 21 Prague 8 Czech Republic Faculty of Nuclear Science and Physical Engineering Czech Technical University Břehová 7 115 19 Prague 1 Czech Republic National Institute of Chemical Physics and Biophysics Akadeemia tee 23 12618 Tallinn Estonia RIKEN Center for Emergent Matter Science (CEMS) Wako 351-0198 Japan Department of Advanced Materials Science University of Tokyo Kashiwa 277-8561 Japan Department of Applied Physics and Tokyo College University of Tokyo Tokyo 113-8656 Japan Experimental Physics V Center for Electronic Correlations and Magnetism University of Augsburg 86135 Augsburg Germany Institute for Solid State Physics and Optics Wigner Research Centre for Physics P.O. Box. 49 H-1525 Budapest Hungary Department of Physics and Astronomy University of California Irvine 4129 Frederick Reines Hall Irvine California 92697 USA Hungarian Academy of Sciences Premium Postdoctor Program 1051 Budapest Hungary

Nonreciprocal directional dichroism, also called the optical-diode effect, is an appealing functional property inherent to the large class of noncentrosymmetric magnets. However, the in situ electric control of this phenomenon is challenging as it requires a set of conditions to be fulfilled: Special symmetries of the magnetic ground state, spin excitations with comparable magnetic- and electric-dipole activity, and switchable electric polarization. We demonstrate the isothermal electric switch between domains of Ba2CoGe2O7 possessing opposite magnetoelectric susceptibilities. Combining THz spectroscopy and multiboson spin-wave analysis, we show that unbalancing the population of antiferromagnetic domains generates the nonreciprocal light absorption of spin excitations.

关键词： Magnetoelectric effect Magnons Optical & microwave phenomena Antiferromagnets Multiferroics

Graphene composites as efficient electromagnetic absorbers in the extremely high frequency band

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arXiv 2020年

作者： Barani, Zahra Kargar, Fariborz Godziszewski, Konrad Rehman, Adil Yashchyshyn, Yevhen Rumyantsev, Sergey Cywiński, Grzegorz Knap, Wojciech Balandin, Alexander A. Department of Electrical and Computer Engineering University of California RiversideCA92521 United States Center Materials Science and Engineering Program University of California RiversideCA92521 United States Institute of Radioelectronics and Multimedia Technology Warsaw University of Technology Warsaw00-665 Poland CENTERA Laboratories Institute of High-Pressure Physics Polish Academy of Sciences Warsaw01-142 Poland CEZAMAT Warsaw University of Technology Warsaw02-822 Poland

We report on the synthesis of the epoxy-based composites with graphene fillers and testing their electromagnetic shielding efficiency by the quasi-optic free-space method in the extremely high frequency (EHF) band (220 - 325 GHz). The curing adhesive composites were produced by a scalable technique with a mixture of single-layer and few-layer graphene layers of a few-micron lateral dimensions. It was found that the electromagnetic transmission, TT, is low even at small concentrations of graphene fillers: TT Copyright © 2020, The Authors. All rights reserved.

关键词： Graphene

SpringerBriefs in Applied Sciences and Technology

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Preface

SpringerBriefs in Applied sciences and Technology 2020年 v页

作者： Rezaie, Hamid Reza Esnaashary, Mohammad Hossein Karfarma, Masoud Öchsner, Andreas Ceramic and Biomaterial Division Department of Engineering Materials Iran University of Science and Technology Tehran Iran Faculty of Mechanical Engineering Esslingen University of Applied Sciences Esslingen am NeckarBaden-Württemberg Germany

Unifying femtosecond and picosecond single-pulse magnetic switching in GdFeCo

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arXiv 2020年

作者： Jakobs, F. Ostler, T.A. Lambert, C.-H. Yang, Y. Salahuddin, S. Wilson, R.B. Gorchon, J. Bokor, J. Atxitia, U. Dahlem Center for Complex Quantum Systems and Fachbereich Physik Freie Universität Berlin Berlin14195 Germany LiégeB-4000 Belgium College of Business Technology and Engineering Sheffield Hallam University Howard Street SheffieldS1 1WB United Kingdom Department of Electrical Engineering and Computer Sciences University of California BerkeleyCA94720 United States Department of Materials Science and Engineering University of California BerkeleyCA94720 United States Lawrence Berkeley National Laboratory 1 Cyclotron Road BerkeleyCA94720 United States Department of Mechanical Engineering and Materials Science and Engineering Program University of California RiversideCA92521 United States ETH Zurich Hönggerbergring 64 Zürich8093 Switzerland Portland Technology Development Department Intel Corp. HillsboroOR97006 United States Universite de Lorraine CNRS IJL NancyF-54000 France

Many questions are still open regarding the physical mechanisms behind the magnetic switching in GdFeCo alloys by single optical pulses. Phenomenological models suggest a femtosecond scale exchange relaxation between sublattice magnetization as the driving mechanism for switching. The recent observation of thermally induced switching in GdFeCo by using both several picosecond optical laser pulse as well as electric current pulses has questioned this previous understanding. This has raised the question of whether or not the same switching mechanics are acting at the femoand picosecond scales. In this work, we aim at filling this gap in the understanding of the switching mechanisms behind thermal single-pulse switching. To that end, we have studied experimentally thermal single-pulse switching in GdFeCo alloys, for a wide range of system parameters, such as composition, laser power and pulse duration. We provide a quantitative description of the switching dynamics using atomistic spin dynamics methods with excellent agreement between the model and our experiments across a wide range of parameters and timescales, ranging from femtoseconds to picoseconds. Furthermore, we find distinct element-specific damping parameters as a key ingredient for switching with long picosecond pulses and argue, that switching with pulse durations as long as 15 picoseconds is possible due to a low damping constant of Gd. Our findings can be easily extended to speed up dynamics in other contexts where ferrimagnetic GdFeCo alloys have been already demonstrated to show fast and energy-efficient processes, e.g. domain-wall motion in a track and spin-orbit torque switching in spintronics devices. Copyright © 2020, The Authors. All rights reserved.

关键词： Ternary alloys

Large-scale orientational order in bacterial colonies during inward growth

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arXiv 2020年

作者： Basaran, Mustafa Yaman, Y. Ilker Yüce, Tevfik Can Vetter, Roman Kocabas, Askin Department of Physics Koç University Sarıyer Istanbul34450 Turkey Bio-Medical Sciences and Engineering Program Koç University Sarıyer Istanbul34450 Turkey Computational Physics for Engineering Materials ETH Zurich Zurich8093 Switzerland Koç University Surface Science and Technology Center Koç University Sarıyer Istanbul34450 Turkey Koç University Research Center for Translational Medicine Koç University Sarıyer Istanbul34450 Turkey

During colony growth, complex interactions regulate the bacterial orientation, leading to the formation of large-scale ordered structures, including topological defects, microdomains, and branches. These structures may benefit bacterial strains, providing invasive advantages during colonization. Active matter dynamics of growing colonies drives the emergence of these ordered structures. However, additional biomechanical factors also play a significant role during this process. Here we show that the velocity profile of growing colonies creates strong radial orientation during inward growth when crowded populations invade a closed area. During this process, growth geometry sets virtual confinement and dictates the velocity profile. Herein, flow-induced alignment and torque balance on the rod-shaped bacteria result in a new stable orientational equilibrium in the radial direction. Our analysis revealed that the dynamics of these radially oriented structures also known as aster defects, depend on bacterial length and can promote the survival of the longest bacteria around localized nutritional hot spots. The present results indicate a new mechanism underlying structural order and provide mechanistic insights into the dynamics of bacterial growth on complex surfaces. Copyright © 2020, The Authors. All rights reserved.

关键词： Bacteria

BPS2025 - Single-cell mass-based mixture model for perturbation response characterization in breast cancer

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Biophysical Journal 2025年第3期124卷 639a-639a页

作者： Fakhar U. Singhera Robert Kimmerling Xingyao Chen Leigh Campbell Jonathan Katz Reva Basho Justin Wells Albert Kovatich Michael F. Press Jerry S. Lee Mork Family Department of Chemical Engineering and Materials Science University of Southern California Los Angeles CA USA Travera Inc. Medford MA USA Ellison Institute of Technology Los Angeles CA USA Murtha Cancer Center Research Program Department of Surgery Uniformed Services University of the Health Sciences Bethseda MD USA The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc. Bethseda MD USA Department of Medicine Keck School of Medicine University of Southern California Los Angeles CA USA Division of Surgical Oncology Walter Reed National Military Medical Center Bethseda MD USA Department of Pathology Keck School of Medicine University of Southern California Los Angeles CA USA

Microscopic mechanism of van der Waals heteroepitaxy in the formation of MoS2/hBN vertical heterostructures

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arXiv 2020年

作者： Okada, Mitsuhiro Maruyama, Mina Okada, Susumu Warner, Jamie H. Kureishi, Yusuke Uchiyama, Yosuke Taniguchi, Takashi Watanabe, Kenji Shimizu, Tetsuo Kubo, Toshitaka Shinohara, Hisanori Kitaura, Ryo Tsukuba Ibaraki305-8565 Japan Graduate School of Pure and Applied Sciences University of Tsukuba Tsukuba Ibaraki305-8571 Japan Walker Department of Mechanical Engineering University of Texas at Austin 204 East Dean Keeton Street AustinTX78712 United States Materials Graduate Program Texas Materials Institute University of Texas at Austin 204 East Dean Keeton Street AustinTX78712 United States Department of Chemistry Nagoya University Nagoya Aichi464-8602 Japan International Center for Materials Nanoarchitectonics National Institute for Materials Science Tsukuba Ibaraki305-0044 Japan Research Center for Functional Materials National Institute for Materials Science Tsukuba Ibaraki305-0044 Japan

Recent works have revealed that van der Waals (vdW) heteroepitaxial growth of 2D materials on crystalline substrates, such as hexagonal boron nitride (hBN), leads to formation of self-aligned grains, which results in defect-free stitching between the grains. However, how the weak vdW interaction causes strong limitation on crystal orientation of grains is still not understood yet. In this work, we have focused on investigation of microscopic mechanism of self-alignment of MoS2 grains in vdW epitaxial growth on hBN. Through calculation based on density functional theory and the Lennard-Jones potential, we found that interlayer energy between MoS2 and hBN strongly depends both on size and crystal orientation of MoS2. We also found that, when size of MoS2 is ca. 40 nm, rotational energy barrier can exceed ~ 1 eV, which should suppress rotation to align crystal orientation of MoS2 even at growth temperature. Copyright © 2020, The Authors. All rights reserved.

关键词： Van der Waals forces

Highly Recyclable and Tough Elastic Vitrimers from a Defined Polydimethylsiloxane Network

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Angewandte Chemie 2023年第47期135卷

作者： Dr. Jiancheng Luo Dr. Xiao Zhao Hao Ju Dr. Xiangjun Chen Dr. Sheng Zhao Dr. Zoriana Demchuk Dr. Bingrui Li Dr. Vera Bocharova Dr. Jan-Michael Y. Carrillo Dr. Jong K. Keum Prof. Sheng Xu Prof. Alexei P. Sokolov Dr. Jiayao Chen Prof. Peng-Fei Cao Chemical Sciences Division Oak Ridge National Laboratory Oak Ridge TN-37830 USA State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical Technology Beijing 100029 China Materials Science and Engineering Program University of California San Diego La Jolla CA-92093 USA Department of Chemistry University of Tennessee Knoxville TN-37996 USA The Bredesen Center for Interdisciplinary Research and Graduate Education University of Tennessee Knoxville TN-37996 USA Center for Materials Sciences Oak Ridge National Laboratory Oak Ridge TN-37830 USA Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge TN-37830 USA

Despite intensive research on sustainable elastomers, achieving elastic vitrimers with significantly improved mechanical properties and recyclability remains a scientific challenge. Herein, inspired by the classical elasticity theory, we present a design principle for ultra-tough and highly recyclable elastic vitrimers with a defined network constructed by chemically crosslinking the pre-synthesized disulfide-containing polydimethylsiloxane (PDMS) chains with tetra-arm polyethylene glycol (PEG). The defined network is achieved by the reduced dangling short chains and the relatively uniform molecular weight of network strands. Such elastic vitrimers with the defined network, i.e., PDMS-disulfide-D, exhibit significantly improved mechanical performance than random analogous, previously reported PDMS vitrimers, and even commercial silicone-based thermosets. Moreover, unlike the vitrimers with random network that show obvious loss in mechanical properties after recycling, those with the defined network enable excellent thermal recyclability. The PDMS-disulfide-D also deliver comparable electrochemical signals if utilized as substrates for electromyography sensors after the recycling. The multiple relaxation processes are revealed via a unique physical approach. Multiple techniques are also applied to unravel the microscopic mechanism of the excellent mechanical performance and recyclability of such defined network.

关键词： Defined Network Polydimethylsiloxane Recyclable Polymer Tough Elastomer Vitrimers

EMPRESS. IX. Extremely Metal-Poor Galaxies are Very Gas-Rich Dispersion-Dominated Systems: Will JWST Witness Gaseous Turbulent High-z Primordial Galaxies?

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arXiv 2022年

作者： Isobe, Yuki Ouchi, Masami Nakajima, Kimihiko Ozaki, Shinobu Bouché, Nicolas F. Wise, John H. Xu, Yi Emsellem, Eric Kusakabe, Haruka Hattori, Takashi Nagao, Tohru Chiaki, Gen Fukushima, Hajime Harikane, Yuichi Hayashi, Kohei Hirai, Yutaka Kim, Ji Hoon Maseda, Michael V. Nagamine, Kentaro Shibuya, Takatoshi Sugahara, Yuma Yajima, Hidenobu Aoyama, Shohei Fujimoto, Seiji Fukushima, Keita Hatano, Shun Inoue, Akio K. Ishigaki, Tsuyoshi Kawasaki, Masahiro Kojima, Takashi Komiyama, Yutaka Koyama, Shuhei Koyama, Yusei Lee, Chien-Hsiu Matsumoto, Akinori Mawatari, Ken Moriya, Takashi J. Motohara, Kentaro Murai, Kai Nishigaki, Moka Onodera, Masato Ono, Yoshiaki Rauch, Michael Saito, Tomoki Sasaki, Rin Suzuki, Akihiro Takeuchi, Tsutomu T. Umeda, Hiroya Umemura, Masayuki Watanabe, Kuria Yabe, Kiyoto Zhang, Yechi Institute for Cosmic Ray Research The University of Tokyo 5-1-5 Kashiwanoha Chiba Kashiwa277-8582 Japan Department of Physics Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo Tokyo113-0033 Japan National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan University of Tokyo Chiba Kashiwa277-8583 Japan Univ Lyon Univ Lyon1 ENS de Lyon CNRS Centre de Recherche Astrophysique de Lyon UMR5574 Saint-Genis-LavalF-69230 France Center for Relativistic Astrophysics School of Physics Georgia Institute of Technology AtlantaGA30332 United States Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo Tokyo113-0033 Japan European Southern Observatory Karl-Schwarzschild-Straße 2 Garching85748 Germany Observatoire de Genéve Université de Genéve 51 Ch. des Maillettes Versoix1290 Switzerland 650 North A'ohoku Place HiloHI96720 United States Research Center for Space and Cosmic Evolution Ehime University Bunkyo-cho 2-5 Ehime Matsuyama790-8577 Japan Center for Computational Sciences University of Tsukuba Ten-nodai 1-1-1 Tsukuba Ibaraki305-8577 Japan Department of Physics and Astronomy University College London Gower Street LondonWC1E 6BT United Kingdom National Institute of Technology Ichinoseki College Hagisho Ichinoseki021-8511 Japan Astronomical Institute Tohoku University 6-3 Aoba Aramaki Aoba-ku Miyagi Sendai980-8578 Japan Department of Physics and Astronomy University of Notre Dame 225 Nieuwland Science Hall Notre DameIN46556 United States Astronomy Program Department of Physics and Astronomy Seoul National University 1 Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of SNU Astronomy Research Center Seoul National University 1 Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of Department of Astronomy University of Wisconsin-Madison 475 N. Charter Street MadisonWI53706 United States Theoretical Astrophysics Department of Earth & Space S

We present kinematics of 6 local extremely metal-poor galaxies (EMPGs) with low metallicities (0.016 − 0.098 Z☉) and low stellar masses (104.7 − 107.6M☉). Taking deep medium-high resolution (R ∼ 7500) integral-field spectra with 8.2-m Subaru, we resolve the small inner velocity gradients and dispersions of the EMPGs with Hα emission. Carefully masking out sub-structures originated by inflow and/or outflow, we fit 3-dimensional disk models to the observed Hα flux, velocity, and velocity-dispersion maps. All the EMPGs show rotational velocities (vrot) of 5-23 km s−1 smaller than the velocity dispersions (σ0) of 17-31 km s−1, indicating dispersion-dominated (vrot/σ0 = 0.29−0.80 gas 0.9 − 1.0. Comparing our results with other Hα kinematics studies, we find that vrot/σ0 decreases and fgas increases with decreasing metallicity, decreasing stellar mass, and increasing specific star-formation rate. We also find that simulated high-z (z ∼ 7) forming galaxies have gas fractions and dynamics similar to the observed EMPGs. Our EMPG observations and the simulations suggest that primordial galaxies are gas-rich dispersion-dominated systems, which would be identified by the forthcoming James Webb Space Telescope (JWST) observations at z ∼ 7. Copyright © 2022, The Authors. All rights reserved.

关键词： Galaxies