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

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

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Room temperature tunable coupling of single photon emitting quantum dots to localized and delocalized modes in plasmonic nanocavity array

arXiv

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arXiv 2020年

作者： Yadav, Ravindra Kumar Liu, Wenxiao Li, Ran Odom, Teri W. Agarwal, Girish S. Basu, Jaydeep K. Department of Physics Indian Institute of Science Bangalore560012 India Texas A&M University College StationTX77843 United States Shaanxi Province Key Laboratory for Quantum Information and Quantum Optoelectronic Devices Xi0an Jiaotong University Xi0an710049 China Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States Department of Materials Science and Engineering Northwestern LemontIL60439 United States Department of Chemistry Northwestern University EvanstonIL60208 United States

Single photon sources (SPS), especially those based on solid state quantum emitters, are key elements in future quantum technologies. What is required is the development of broadband, high quantum efficiency, room temperature SPS which can also be tunably coupled to optical cavities which could lead to development of all-optical quantum communication platforms. In this regard deterministic coupling of SPS to plasmonic nanocavity arrays has great advantage due to long propagation length and delocalized nature of surface lattice resonances (SLRs). Guided by these considerations, we report experiments on the room temperature tunable coupling of single photon emitting colloidal quantum dots (CQDs) to localised and delocalised modes in plasmonic nanocavity arrays. Using time-resolved photo-luminescence measurement on isolated CQD, we report significant advantage of SLRs in realizing much higher Purcell effect, despite large dephasing of CQDs, with values of ∼ 22 and ∼ 6 for coupling to the lattice and localised modes, respectively. We present measurements on the antibunching of CQDs coupled to these modes with g(2)(0) values in quantum domain providing evidence for an effective cooperative behavior. We present a density matrix treatment of the coupling of CQDs to plasmonic and lattice modes enabling us to model the experimental results on Purcell factors as well as on the antibunching. We also provide experimental evidence of indirect excitation of remote CQDs mediated by the lattice modes and propose a model to explain these observations. Our study demonstrates the possibility of developing nanophotonic platforms for single photon operations and communications with broadband quantum emitters and plasmonic nanocavity arrays since these arrays can generate entanglement between to spatially separated quantum emitters. Copyright © 2020, The Authors. All rights reserved.

关键词： Semiconductor quantum dots

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Analysis of electro-spark alloying methods using one-component special technological environments

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AIP Conference Proceedings 2024年第1期3130卷

作者： Viacheslav B. Tarelnyk Oksana P. Haponova Nataliia V. Tarelnyk Czesław Kundera Andriy V. Zahorulko Technical Service Department Sumy National Agrarian University H. Kondratiieva Str. 160 40021 Sumy Ukraine Applied Material Science and Technology of Constructional Materials Department Sumy State University Rymskogo-Korsakova st. 2 40007 Sumy Ukraine Department of Experimental Mechanics Institute of Fundamental Technological Research Polish Academy of Sciences Pawińskiego St. 5B 02-106 Warsaw Poland Faculty of Mechatronics and Mechanical Engineering Kielce University of Technology aleja Tysiąclecia Państwa Polskiego 7 25-314 Kielce Poland Volodymyr Martsynkovskyy Computational Mechanics Department Sumy State University Rymskogo-Korsakova st. 2 40007 Sumy Ukraine

This paper presents an analysis of various technologies, including such as aluminization, cementation, nitriding, and nitrocementation, to increase the quality parameters of surface layers of parts, performed by electrospark alloying (ESA) and by additional saturation of surfaces with alloying elements from special technological environments (STE). During aluminization, the thickness of the "white" layer and the diffusion zone, as well as the microhardness, coating continuity and roughness of the surface increased as the discharge energy (Wp) increased. The layer consists of iron-aluminium intermetallics and free aluminium. It has been proposed to perform the ESA process with the same electrode (aluminium), but at lower energies, in order to reduce the surface roughness and obtain continuous coatings. The comparative study of the parameters of the quality of the layers after the traditional cementation - ESA with carbon electrode (CESA) and after the proposed one has shown that after the treatment of the surface with the use of the proposed technology, the roughness of the surface decreases. Simultaneously, the continuity of the doped layer increases up to 100%, the depth of the carbon diffusion zone increases up to 80 µm, and the microhardness and "white" layer thickness increase to 9932 MPa and 230 µm, respectively. The analysis of the structure-forming characteristics of the surface layers of carbon steel after ESA nitriding and nitrocarburising using STE has shown that the layer structures obtained consist of the following three areas, such as the non-etchable "white" layer, the modified diffusion zone and the substrate. Thickness, microhardness of the coating zones, integrity of the "white" layer, and surface roughness also increase as the discharge energy increases.

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Terahertz chiral photonic-crystal cavities for Dirac gap engineering in graphene

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Nature Communications 2025年第1期16卷 1-11页

作者： Tay, Fuyang Sanders, Stephen Baydin, Andrey Song, Zhigang Welakuh, Davis M. Alabastri, Alessandro Rokaj, Vasil Dag, Ceren B. Kono, Junichiro Department of Electrical and Computer Engineering Rice University Houston TX United States Applied Physics Graduate Program Smalley–Curl Institute Rice University Houston TX United States Smalley–Curl Institute Rice University Houston TX United States Rice Advanced Materials Institute Rice University Houston TX United States John A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge MA United States Max Planck Institute for the Structure and Dynamics of Matter Hamburg Germany Department of Physics Harvard University Cambridge MA United States ITAMP Harvard-Smithsonian Center for Astrophysics Cambridge MA United States Department of Physics Villanova University Villanova PA United States Department of Physics Indiana University Bloomington IN United States Department of Physics and Astronomy Rice University Houston TX United States Department of Materials Science and NanoEngineering Rice University Houston TX United States

Strong coupling between matter and vacuum electromagnetic fields in a cavity can induce novel quantum phases in thermal equilibrium via symmetry breaking. Particularly intriguing is the coupling with circularly polarized cavity fields, which can break time-reversal symmetry (TRS) and lead to topological bands. This has spurred significant interest in developing chiral cavities that feature broken TRS, especially in the terahertz (THz) frequency range, where various large-oscillator-strength resonances exist. Here, we present a design for high-quality-factor THz chiral photonic-crystal cavities (PCCs) that achieve broken TRS using a magnetoplasma in a lightly doped semiconductor. We incorporate ab initio density functional theory calculations into the derived microscopic model, allowing a realistic estimate of the vacuum-induced gap in graphene when coupled to our chiral cavity. Our calculations show an enhancement in the light–matter interaction due to Dirac nodes and predict an energy gap on the order of 1 meV. The THz chiral PCCs offer a promising platform for exploring cavity-dressed condensed matter with broken TRS. © The Author(s) 2025.

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Phonons become chiral in the pseudogap phase of cuprates

arXiv

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arXiv 2020年

作者： Grissonnanche, G. Thériault, S. Gourgout, A. Boulanger, M.-E. Lefrançois, E. Ataei, A. Laliberté, F. Dion, M. Zhou, J.-S. Pyon, S. Takayama, T. Takagi, H. Doiron-Leyraud, N. Taillefer, L. Département de Physique Institut Quantique RQMP Université de Sherbrooke SherbrookeQC Canada Materials Science and Engineering Program Department of Mechanical Engineering University of Texas AustinTX United States Department of Advanced Materials Science University of Tokyo Kashiwa Japan Department of Applied Physics University of Tokyo Tokyo Japan Max Planck Institute for Solid State Research Stuttgart Germany Department of Physics University of Tokyo Tokyo Japan Institute for Functional Matter and Quantum Technologies University of Stuttgart Stuttgart Germany Canadian Institute for Advanced Research TorontoON Canada

The nature of the pseudogap phase of cuprates remains a major puzzle1,2. One of its new signatures is a large negative thermal Hall conductivity Èxy , which appears for dopings p below the pseudogap critical doping p*, but whose origin is as yet unknown3. Because this large Èxy is observed even in the undoped Mott insulator La2CuO4, it cannot come from charge carriers, these being localized at p = 0. Here we show that the thermal Hall conductivity of La2CuO4 is roughly isotropic, being nearly the same for heat transport parallel and normal to the CuO2planes, i.e. kzy(T) . (T). This shows that the Hall response must come from phonons, these being the only heat carriers able to move as easily normal and parallel to the planes4. At p > p*, in both La1.6-xNd0.4SrxCuO4and La1.8-xEu0.2SrxCuO4with p = 0.24, we observe no c-axis Hall signal, i.e. zy(T) = 0, showing that phonons have zero Hall response outside the pseudogap phase. The phonon Hall response appears immediately below p*= 0.23, as confirmed by the large Kzy signal we find in La1.6-xNd0.4SrxCuO4with p = 0.21. The microscopic mechanism by which phonons become chiral in cuprates remains to be identified. This mechanism must be intrinsic-from a coupling of phonons to their electronic environment-rather than extrinsic, from structural defects or impurities, as these are the same on both sides of p*. This intrinsic phonon Hall effect provides a new window on quantum materials5 and it may explain the thermal Hall signal observed in other topologically nontrivial insulators6,7. Copyright © 2020, The Authors. All rights reserved.

关键词： Phonons

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Double resonant tunable second harmonic generation in two-dimensional layered materials through band nesting

arXiv

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arXiv 2021年

作者： Biswas, Sudipta Romen Yu, Jin Wang, Zhenwei da Costa, Diego Rabelo Zhao, Chujun Yuan, Shengjun Low, Tony Department of Electrical & Computer Engineering University of Minnesota MinneapolisMN55455 United States Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering Science Shanghai University Shanghai200444 China Institute for Molecules and Materials Radboud University Heijendaalseweg 135 Nijmegen6525AJ Netherlands Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education School of Physics and Technology Wuhan University Wuhan430072 China Departamento de Física Universidade Federal do Ceará Campus do Pici CE Fortaleza60455-900 Brazil Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices School of Physics and Electronics Hunan University Changsha410082 China School of Physics and Astronomy University of Minnesota MinneapolisMN55455 United States

We proposed a mechanism to generate giant anisotropic second harmonic nonlinear response via double resonance effect, achieved through band nesting via electronic bandstructure engineering. The ideal band setup would be a triplet of nested bands separated by the fundamental resonance energy, ~ω. We demonstrate theoretically that the proposed phenomenon can be realized in bilayer SnS by band tuning with perpendicular electrical bias, which maximizes the second harmonic susceptibility by several orders of magnitude. Moreover, the tunability of the polarization anisotropy can be useful for realizing novel polarization-sensitive devices. © 2021, CC BY.

关键词： Harmonic generation

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Bending of Multilayer van der Waals materials

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Physical Review Letters 2019年第11期123卷 116101-116101页

作者： Guorui Wang Zhaohe Dai Junkai Xiao ShiZhe Feng Chuanxin Weng Luqi Liu Zhiping Xu Rui Huang Zhong Zhang CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology Beijing 100190 China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China Hefei 230026 China Department of Aerospace Engineering and Engineering Mechanics The University of Texas at Austin Austin Texas 78712 USA Applied Mechanics Laboratory Department of Engineering Mechanics and Center for Nano and Micro Mechanics Tsinghua University Beijing 100084 China

Out-of-plane deformation patterns, such as buckling, wrinkling, scrolling, and folding, formed by multilayer van der Waals materials have recently seen a surge of interest. One crucial parameter governing these deformations is bending rigidity, on which significant controversy still exists despite extensive research for more than a decade. Here, we report direct measurements of bending rigidity of multilayer graphene, molybdenum disulfide (MoS2), and hexagonal boron nitride (hBN) based on pressurized bubbles. By controlling the sample thickness and bubbling deflection, we observe platelike responses of the multilayers and extract both their Young’s modulus and bending rigidity following a nonlinear plate theory. The measured Young’s moduli show good agreement with those reported in the literature (Egraphene>EhBN>EMoS2), but the bending rigidity follows an opposite trend, Dgraphenematerials.

关键词： Elasticity Mechanical & acoustical properties Mechanical deformation Mechanical properties of membranes Microstructure Surface & interfacial phenomena 2-dimensional systems Graphene Atomic force microscopy Mechanical testing Molecular dynamics Raman spectroscopy

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Revealing the Origin of Transition-Metal Migration in Layered Sodium-Ion Battery Cathodes: Random Na Extraction and Na-Free Layer Formation

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Angewandte Chemie 2023年第12期135卷

作者： Dr. Shiyong Chu Prof. Duho Kim Gwanghyeon Choi Chunchen Zhang Haoyu Li Prof. Wei Kong Pang Yameng Fan Anita M. D'Angelo Prof. Shaohua Guo Prof. Haoshen Zhou College of Engineering and Applied Sciences Jiangsu Key Laboratory of Artificial Functional Materials National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced Microstructures Frontiers Science Center for Critical Earth Material Cycling Nanjing University Nanjing 210023 China Shenzhen Research Institute of Nanjing University Shenzhen 518000 China Department of Mechanical Engineering (Integrated Engineering Program) Kyung Hee University 1732 Deogyeong-daero Giheung-gu Yongin-si Gyeonggi-do 17104 (Republic of Korea Institute for Superconducting & Electronic Materials University of Wollongong Wollongong NSW-2522 Australia Australian Synchrotron Australian Nuclear Science and Technology Organization 800 Blackburn Road Clayton Victoria 3168 Australia

Cation migration often occurs in layered oxide cathodes of lithium-ion batteries due to the similar ion radius of Li and transition metals (TMs). Although Na and TM show a big difference of ion radius, TMs in layered cathodes of sodium-ion batteries (SIBs) can still migrate to Na layer, leading to serious electrochemical degeneration. To elucidate the origin of TM migration in layered SIB cathodes, we choose NaCrO 2 , a typical layered cathode suffering from serious TM migration, as a model material and find that the TM migration is derived from the random desodiation and subsequent formation of Na-free layer at high charge potential. A Ru/Ti co-doping strategy is developed to address the issue, where the doped active Ru is first oxidized to create a selective desodiation and the doped inactive Ti can function as a pillar to avoid complete desodiation in Ru-contained TM layers, leading to the suppression of the Na-free layer formation and subsequent enhanced electrochemical performance.

关键词： Layered Sodium-Ion Battery Cathodes Na-Free Layer Random Na Extraction Selective Na Extraction Transition-Metal Migration

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Shot noise in a strange metal

arXiv

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arXiv 2022年

作者： Chen, Liyang Lowder, Dale T. Bakali, Emine Andrews, Aaron Maxwell Schrenk, Werner Waas, Monika Svagera, Robert Eguchi, Gaku Prochaska, Lukas Wang, Yiming Setty, Chandan Sur, Shouvik Si, Qimiao Paschen, Silke Natelson, Douglas Applied Physics Graduate Program Rice University 6100 Main St. HoustonTX77005 United States Department of Physics and Astronomy Rice Center for Quantum Materials Rice University 6100 Main St. HoustonTX77005 United States Institute of Solid State Physics TU Wien Wiedner Hauptstraße 8-10 Vienna1040 Austria Institute of Solid State Electronics TU Wien Gußhausstraße 25-25a Gebäude CH Vienna1040 Austria Center for Micro and Nanostructures TU Wien Gußhausstraße 25-25a Gebäude CH Vienna1040 Austria Department of Electrical and Computer Engineering Rice University 6100 Main St. HoustonTX77005 United States Department of Materials Science and NanoEngineering Rice University 6100 Main St. HoustonTX77005 United States

Strange-metal behavior has been observed in materials ranging from high-temperature superconductors to heavy fermion metals. In conventional metals, current is carried by quasiparticles;although it has been suggested that quasiparticles are absent in strange metals, direct experimental evidence is lacking. We measured shot noise to probe the granularity of the current-carrying excitations in nanowires of the heavy fermion strange metal YbRh2Si2. When compared with conventional metals, shot noise in these nanowires is strongly suppressed. This suppression cannot be attributed to either electron-phonon or electron-electron interactions in a Fermi liquid, which suggests that the current is not carried by well-defined quasiparticles in the strange-metal regime that we probed. Our work sets the stage for similar studies of other strange metals. Copyright © 2022, The Authors. All rights reserved.

关键词： Nanowires

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New Assembly Method for Cellulose Derived Graphene Quantum Dots-Sensitized Solar Cells

Research Square

引用

Research Square 2021年

作者： Mahalingam, Savisha Lau, Kam Sheng Omar, Azimah Manap, Abreeza Chelvanathan, Puvaneswaran Chia, Chin Hua Amin, Nowshad Mathews, Illona Juliana Afandi, Nurfanizan Abd Rahim, Nasrudin Institute of Sustainable Energy Universiti Tenaga Nasional Jalan IKRAM-UNITENSelangor Kajang43000 Malaysia Materials Science Program Department of Applied Physics Faculty of Science and Technology Universiti Kebangsaan Malaysia Selangor Bangi43600 Malaysia Level 4 Wisma R&D University of Malaya Jalan Pantai Baharu Kuala Lumpur59990 Malaysia Department of Mechanical Engineering College of Engineering Universiti Tenaga Nasional Jalan IKRAM-UNITEN Selangor Kajang43000 Malaysia Solar Energy Research Institute Universiti Kebangsaan Malaysia Jalan IKRAM-UNITEN Selangor Bangi43600 Malaysia Sunway University No. 5 Jalan Universiti Selangor Bandar Sunway47500 Malaysia Renewable Energy Research Group King Abdulaziz University Jeddah21589 Saudi Arabia

Unambiguously layer by layer (LBL) assembly of graphene quantum dots (GQDs) and dye (GQDs/dye) on TiO2 photoanode is the traditional and straightforward approach in the fabrication of graphene quantum dot-sensitized solar cells (QDSSCs). Unfortunately, limited light absorption and low affinity of GQDs to TiO2 surface shadow the advantages of LBL and constrains its practical application. Herein, a new strategy of mixture configuration (GQDs+dye) was investigated. A distinctive nanoporous honeycomb hexagonal carbon network of GQDs was found with fewer defects single crystalline structure, and an average size of 9.87 nm was produced from cellulose. Experimental results demonstrated that LBL exhibited the highest efficiency of 16.76 % under low illumination but a lower efficiency (1.43%) than the mixture method (2.91%) under standard light. The increased Jsc (5.075 mA/cm2) and high charge collection efficiency (0.96) in the mixture sample indicated enhanced electron collection at TiO2. The less -OH groups on TiO2 provides a good surface intact of GQDs and N719. In addition to that, the high surface potential (33.47 mV) of the premixed sample restricted the photogenerated electrons to go into a deep state, reducing back electron transfer. Therefore, mixture assembly of co-sensitization is an effective approach for light-harvesting in QDSSC. © 2021, CC BY.

关键词： Dye-sensitized solar cells

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