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Frequency-tunable transmon in a three-dimensional copper cavity

Chinese Physics B 2015年第11期24卷 81-84页

作者：潘佳政曹志敏范云益周渝兰栋刘宇浩陈志平李永超曹春海许伟伟康琳陈健于海峰于扬孙国柱吴培亨 National Laboratory of Solid State Microstructures and Research Institute of Superconductor Electronics School of Electronic Science and Engineering Nanjing University Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China National Laboratory of Solid State Microstructures School of Physics Nanjing University

We have realized a frequency-tunable transmon in a three-dimensional cooper cavity using a direct current supercon- ducting quantum interference device. Both the transition frequency of the transmon and the frequency of the dressed cavity can be varied with the applied external flux bias, which are well consistent with the theoretical model. The range of the variable transition frequency is from 5.188 GHz to 7.756 GHz. The energy relaxation time of the transmon is hundreds of nanoseconds.

关键词： superconducting qubit three-dimensional transmon tunable transmon dc-superconducting quantum interference device

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Microstructure, Thermal, Mechanical, and Dielectric Properties of BaO–CaO–Al2O3–B2O3–SiO2 Glass-Ceramics

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IOP Conference Series: materials science and engineering 2017年第1期275卷

作者： Bo Li Haibo Bian Yi Fang School of Microelectronics and Solid-State Electronics University of Electronic Science and Technology of China Chengdu 610054 China State Key Laboratory of Electronic Thin Films and Integrated Devices Chengdu 610054 China National Engineering Research Center of Electromagnetic Radiation Control Materials Chengdu 610054 China

BaO–CaO–Al2O3–B2O3–SiO2 (BCABS) glass-ceramics were prepared via the method of controlled crystallization. The effect of CaO modification on the microstructure, phase evolution, as well as thermal, mechanical, and dielectric properties was investigated. XRD identified that quartz is the major crystal phase; cristobalite and bazirite are the minor crystal phases. Moreover, the increase of CaO could inhibit the phase transformation from quartz to cristobalite, but excessive CaO would increase the porosity of the ceramics. Additionally, with increasing the amount of CaO, the thermal expansion curve tends to be linear, and subsequently the CTE value decreases gradually, which is attributed to the decrease of cristobalite with high CTE and the formation of CaSiO3 with low CTE. The results indicated that a moderate amount of CaO helps attaining excellent mechanical, thermal, and dielectric properties, that is, the specimen with 9 wt% CaO sintered at 950 °C has a high CTE value (11.5 × 10–6/°C), a high flexural strength (165.7 MPa), and good dielectric properties (εr = 6.2, tanδ = 1.8 × 10–4, ρ = 4.6 × 1011 Ωcm).

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High-field magnetization and magnetic phase diagram of α-Cu2V2O7

arXiv

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arXiv 2017年

作者： Gitgeatpong, G. Suewattana, M. Zhang, Shiwei Miyake, A. Tokunaga, M. Chanlert, P. Kurita, N. Tanaka, H. Sato, T.J. Zhao, Y. Matan, K. Department of Physics Faculty of Science Mahidol University Bangkok10400 Thailand ThEP Commission of Higher Education Bangkok10400 Thailand Physics Program Faculty of Science and Technology Phranakhon Rajabhat University Bangkok10220 Thailand Department of Physics College of William and Mary WilliamsburgVA23187-8795 United States Institute for Solid State Physics University of Tokyo Kashiwa277-8581 Japan Department of Physics Tokyo Institute of Technology Meguro-ku Tokyo152-8551 Japan IMRAM Tohoku University Sendai Miyagi980-8577 Japan Department of Materials Science and Engineering University of Maryland College ParkMD20742 United States NIST Center for Neutron Research National Institute of Standards and Technology GaithersburgMD20899 United States

High-field magnetization of the spin-1/2 antiferromagnet α-Cu2V2O7 was measured in pulsed magnetic fields of up to 56 T in order to study its magnetic phase diagram. When the field was applied along the easy axis (the a-axis), two distinct transitions were observed at Hc1 = 6.5 T and Hc2 = 18.0 T. The former is a spin-flop transition typical for a collinear antiferromagnet and the latter is believed to be a spin-flip transition of canted moments. The canted moments, which are induced by the Dzyaloshinskii-Moriya interactions, anti-align for Hc1 Copyright © 2017, The Authors. All rights reserved.

关键词： Antiferromagnetic materials

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Pressure tuning of bond-directional exchange interactions and magnetic frustration in the hyperhoneycomb iridate β−Li2IrO3

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Physical Review B 2017年第14期96卷 140402(R)-140402(R)页

作者： L. S. I. Veiga M. Etter K. Glazyrin F. Sun C. A. Escanhoela, Jr. G. Fabbris J. R. L. Mardegan P. S. Malavi Y. Deng P. P. Stavropoulos H.-Y. Kee W. G. Yang M. van Veenendaal J. S. Schilling T. Takayama H. Takagi D. Haskel Deutsches Elektronen-Synchrotron (DESY) D-22607 Hamburg Germany Advanced Photon Source Argonne National Laboratory Argonne Illinois 60439 USA London Centre for Nanotechnology and Department of Physics and Astronomy University College London Gower Street London WC1E 6BT United Kingdom Center for High Pressure Science & Technology Advanced Research (HPSTAR) Shanghai 201203 China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China Brazilian Synchrotron Light Laboratory (LNLS) Brazilian Center for Research in Energy and Materials (CNPEM) Campinas SP 13083-970 Brazil Department of Physics Washington University St. Louis Missouri 63130 USA Department of Condensed Matter Physics and Materials Science Brookhaven National Laboratory Upton New York 11973 USA Department of Physics and Center for Quantum Materials University of Toronto 60 St. George Street Toronto Ontario Canada M5S 1A7 Canadian Institute for Advanced Research/Quantum Materials Program Toronto Ontario Canada M5G 1Z8 High Pressure Synergetic Consortium (HPSynC) Geophysical Laboratory Carnegie Institution of Washington Argonne Illinois 60439 USA Department of Physics Northern Illinois University De Kalb Illinois 60115 USA Max Planck Institute for Solid State Research Heisenbergstrasse 1 D-70569 Stuttgart Germany Department of Physics and Department of Advanced Materials University of Tokyo 7-3-1 Hongo Tokyo 113-0033 Japan

We explore the response of Ir 5d orbitals to pressure in β−Li2IrO3, a hyperhoneycomb iridate in proximity to a Kitaev quantum spin-liquid (QSL) ground state. X-ray absorption spectroscopy reveals a reconstruction of the electronic ground state below 2 GPa, the same pressure range where x-ray magnetic circular dichroism shows an apparent collapse of magnetic order. The electronic reconstruction, which manifests a reduction in the effective spin-orbit interaction in 5d orbitals, pushes β−Li2IrO3 further away from the pure Jeff=1/2 limit. Although lattice symmetry is preserved across the electronic transition, x-ray diffraction shows a highly anisotropic compression of the hyperhoneycomb lattice which affects the balance of bond-directional Ir-Ir exchange interactions driven by spin-orbit coupling at Ir sites. An enhancement of symmetric anisotropic exchange over Kitaev and Heisenberg exchange interactions seen in theoretical calculations that use precisely this anisotropic Ir-Ir bond compression provides one possible route to the realization of a QSL state in this hyperhoneycomb iridate at high pressures.

关键词： Electronic structure Magnetic interactions Quantum spin liquid Spin-orbit coupling Ab initio calculations Pressure techniques X-ray absorption spectroscopy

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Magnetic structure of the magnetoelectric material Ca2CoSi2O7

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Physical Review B 2017年第17期95卷 174431-174431页

作者： A. Sazonov V. Hutanu M. Meven G. Roth H. Murakawa Y. Tokura V. K. Guduru L. C. J. M. Peters U. Zeitler L. F. Kiss D. Szaller B. Náfrádi I. Kézsmárki Institute of Crystallography RWTH Aachen University and Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ) 85747 Garching Germany Institute of Crystallography RWTH Aachen University 52056 Aachen Germany Multiferroics Project ERATO Japan Science and Technology Agency (JST) University of Tokyo Tokyo 113-8656 Japan Department of Physics Osaka University 560-0043 Osaka Japan Department of Applied Physics and Quantum Phase Electronics Center (QPEC) University of Tokyo Tokyo 113-8656 Japan RIKEN Center for Emergent Matter Science (CEMS) Wako 351-0198 Japan High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials Radboud University 6525 ED Nijmegen The Netherlands Institute for Solid State Physics and Optics Wigner Research Centre for Physics Hungarian Academy of Sciences 1525 Budapest Hungary Department of Physics Budapest University and Economics of Technology and MTA-BME Lendület Magneto-optical Spectroscopy Research Group 1111 Budapest Hungary École Polytechnique Fédérale de Lausanne Laboratory of Nanostructures and Novel Electronic Materials 1015 Lausanne Switzerland

Detailed investigation of Ca2CoSi2O7 was performed in its low-temperature magnetoelectric state combining neutron diffraction with magnetization measurements on single crystals. The crystal and magnetic structures well below the antiferromagnetic transition temperature of TN≈5.7 K were determined using neutron diffraction. Neutron diffraction data imply no structural phase transition from 10 K down to 2.5 K and are well described within the orthorhombic space group P21212 with a 3×3×1 supercell compared with the high-temperature unmodulated state (tetragonal space group P4¯21m). We found that in zero magnetic field the magnetic space group is P2121′2′ with antiferromagnetic order along the [100] or [010] axes for two types of 90∘ twin domains, while neighboring spins along the [001] axis are ordered ferromagnetically. A noncollinear spin arrangement due to small canting within the ab plane is allowed by symmetry and leads to the existence of the tiny spontaneous magnetization below TN. The ordered moment with a magnitude of about 2.8 μB/Co2+ at 2.5 K lies in the ab plane. Distinct differences between the magnetic structure of Ca2CoSi2O7 as compared to those of Ba2CoGe2O7 and Sr2CoSi2O7 are discussed.

关键词： Magnetism Multiferroics Magnetization measurements Neutron diffraction

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Magnetoelectric memory function with optical readout

arXiv

引用

arXiv 2017年

作者： Kocsis, V. Penc, K. Rõõm, T. Nagel, U. Vít, J. Romhányi, J. Tokunaga, Y. Taguchi, Y. Tokura, Y. Kézsmárki, I. Bordács, S. Wako Saitama351-0198 Japan Department of Physics Budapest University of Technology and Economics and MTA-BME Lendület Magneto-optical Spectroscopy Research Group Budapest1111 Hungary Institute for Solid State Physics and Optics Wigner Research Centre for Physics Hungarian Academy of Sciences P.O.B. 49 BudapestH-1525 Hungary National Institute of Chemical Physics and Biophysics Tallinn12618 Estonia Institute of Physics ASCR Na Slovance 2 Prague 8182 21 Eue Faculty of Nuclear Science and Physical Engineering Czech Technical University Břehová 7 Prague 1115 19 Eue Okinawa Institute of Science and Technology Graduate University Onna-sonOkinawa904-0395 Japan Department of Advanced Materials Science University of Tokyo Kashiwa277-8561 Japan Quantum-Phase Electronics Center Department of Applied Physics University of Tokyo Tokyo113-8656 Japan Department of Applied Physics University of Tokyo Hongo Tokyo113-8656 Japan Experimental Physics 5 Center for Electronic Correlations and Magnetism Institute of Physics University of Augsburg Augsburg86159 Germany Hungarian Academy of Sciences Premium Postdoctor Program Budapest1051 Hungary

The ultimate goal of multiferroic research is the development of new-generation non-volatile memory devices1, the so-called magnetoelectric (ME) memories, where magnetic bits are controlled via electric fields without the application of electrical currents subject to dissipation. This low-power operation exploits the entanglement of the magnetization and the electric polarization coexisting in multiferroic materials2,3. Here we demonstrate the optical readout of ME memory states in the antiferromagnetic (AFM) and antiferroelectric (AFE) LiCoPO4, based on the strong absorption difference of THz radiation between its two types of ME domains. This unusual contrast is attributed to the dynamic ME effect of the spin-wave excitations, as confirmed by our microscopic model, which also captures the characteristics of the observed static ME effect. Our proof-of-principle study, demonstrating the control and the optical readout of ME domains in LiCoPO4, lays down the foundation for future ME memory devices based on antiferroelectric-antiferromagnetic insulators. Copyright © 2017, The Authors. All rights reserved.

关键词： Digital storage

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Study of structure and properties of polymer composites based on polytetrafluoroethylene and cobalt nanoparticles

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Inorganic materials: Applied research 2015年第2期6卷 179-186页

作者： Baronin, G.S. Buznik, V.M. Yurkov, G. Yu. Zavrazhin, D.O. Kobzev, D.E. Khudyakov, V.V. Mescheryakova, Yu. V. Fionov, A.S. Ovchenkov, E.A. Ashmarin, A.A. Biryukova, M.I. Tambov State Technical University Tambov Russia Research and Educational Center Solid-Phase Technologies Moscow Russia Baikov Institute of Metallurgy and Materials Science Russian Academy of Sciences Moscow Russia Moscow Russia Kotel’nikov Institute of Radio Engineering and Electronics Russian Academy of Sciences Moscow Russia Moscow State University Moscow Russia

This work discusses the study of structure and properties of composites based on polytetrafluoroethylene (PTFE) and filler, which is a composite material of cobalt nanoparticles and ultrafine polytetrafluoroethylene (UF PTFE). Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray phase analysis (XRF) are applied for complex investigation into the properties of the obtained composite materials, such as specific energy absorption rate, thermal resistance and internal orientational stresses, thermophysical properties, and dielectric permeability. It is demonstrated that the obtained composite materials are superior to the initial matrix—PTFE. The magnetic study of the composite materials confirms the occurrence of metal nanoparticles and their interaction with the polymer matrix. © 2015, Pleiades Publishing, Ltd.

关键词： Thermodynamic properties

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Probing Carrier Transport and Structure-Property Relationship of Highly Ordered Organic Semiconductors at the Two-Dimensional Limit

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Physical Review Letters 2016年第1期116卷 016602-016602页

作者： Yuhan Zhang Jingsi Qiao Si Gao Fengrui Hu Daowei He Bing Wu Ziyi Yang Bingchen Xu Yun Li Yi Shi Wei Ji Peng Wang Xiaoyong Wang Min Xiao Hangxun Xu Jian-Bin Xu Xinran Wang National Laboratory of Solid State Microstructures School of Electronic Science and Engineering and Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices Renmin University of China Beijing 100872 China College of Engineering and Applied Sciences Nanjing University Nanjing 210093 China School of Physics Nanjing University Nanjing 210093 China Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China and Collaborative Innovation Center of Advanced Microstructures Nanjing 210093 China Department of Physics University of Arkansas Fayetteville Arkansas 72701 USA CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and Engineering University of Science and Technology of China Hefei 230026 China Department of Electronic Engineering and Materials Science and Technology Research Center The Chinese University of Hong Kong Hong Kong SAR China

One of the basic assumptions in organic field-effect transistors, the most fundamental device unit in organic electronics, is that charge transport occurs two dimensionally in the first few molecular layers near the dielectric interface. Although the mobility of bulk organic semiconductors has increased dramatically, direct probing of intrinsic charge transport in the two-dimensional limit has not been possible due to excessive disorders and traps in ultrathin organic thin films. Here, highly ordered single-crystalline mono- to tetralayer pentacene crystals are realized by van der Waals (vdW) epitaxy on hexagonal BN. We find that the charge transport is dominated by hopping in the first conductive layer, but transforms to bandlike in subsequent layers. Such an abrupt phase transition is attributed to strong modulation of the molecular packing by interfacial vdW interactions, as corroborated by quantitative structural characterization and density functional theory calculations. The structural modulation becomes negligible beyond the second conductive layer, leading to a mobility saturation thickness of only ∼3 nm. Highly ordered organic ultrathin films provide a platform for new physics and device structures (such as heterostructures and quantum wells) that are not possible in conventional bulk crystals.

关键词： Electrical conductivity Van der Waals interaction 2-dimensional systems Multilayer thin films Organic semiconductors Atomic force microscopy Transmission electron microscopy Transport techniques

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A Stable Saddle‐Shaped Polycyclic Hydrocarbon with an Open‐Shell Singlet Ground state

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Angewandte Chemie 2017年第12期129卷

作者： Ji Ma Junzhi Liu Martin Baumgarten Yubin Fu Yuan‐Zhi Tan Karl Sebastian Schellhammer Frank Ortmann Gianaurelio Cuniberti Hartmut Komber Reinhard Berger Klaus Müllen Xinliang Feng Center for Advancing Electronics Dresden (cfaed) Department of Chemistry and Food Chemistry Technische Universität Dresden 01062 Dresden Germany Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University 361005 Xiamen China Institute for Materials Science Max Bergmann Center of Biomaterials Dresden Center for Computational Materials Science Technische Universität Dresden 01062 Dresden Germany Leibniz-Institut für Polymerforschung Dresden e. V. Hohe Strasse 6 01069 Dresden Germany

Diindeno‐fused bischrysene, a new diindeno‐based polycyclic hydrocarbon (PH), was synthesized and characterized. It was elucidated in detailed experimental and theoretical studies that this cyclopenta‐fused PH possesses an open‐shell singlet biradical structure in the ground state and exhibits high stability under ambient conditions ( t 1/2 =39 days). The crystal structure unambiguously shows a novel saddle‐shaped π‐conjugated carbon skeleton due to the steric hindrance of the central cove‐edged bischrysene unit. UV/Vis spectral measurements revealed that the title molecule has a very narrow optical energy gap of 0.92 eV, which is consistent with the electrochemical analysis and further supported by density functional theory (DFT) calculations.

关键词： Aromatizität Biradikale Elektronenstruktur Polycyclische Kohlenwasserstoffe Sattelkonformation

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Dicyanovinyl-unit-induced absorption enhancement of iridium(III) complexes in long-wavelength range and potential application in dye-sensitized solar cells

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science China Chemistry 2015年第4期58卷 658-665页

作者： Dongdong Wang Hua Dong Xiaoyu Zhang Yong Wu Shaohua Shen Bo Jiao Zhaoxin Wu Min Gao Geng Wang Department of Applied Chemistry School of Science Xi’an Jiaotong University Key Laboratory for Physical Electronics and Devices of the Ministry of Education School of Electronic and information Engineering Xi’An Jiaotong University Key Laboratory for Advanced Materials Institute of Fine Chemicals and Department of Chemistry East China University of Science and Technology International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University

Iridium complexes with dicyanovinyl-grafted phenylpyridine/l-phenylisoquinoline as ligands are synthesized and their photo- physical, electrochemical, and sensitization properties in DSSCs are investigated. The iridium complexes present significantly enhanced absorption from 400 to 525 nm. The 1-phenylisoquinoline-based iridium complex show bathochromic-shift emission in DMSO solution compared with their phenylpyridine-based counterpart, while their absorption response and photoluminescence peak in solid show little difference despite extension of the conjugated system. Using DSSCs, the conversion efficiency of 0.62% and open-circuit current of 1.4 mA/cm2 is achieved. The poor performance is attributed to the excited-state properties of iridium complexes according to the TD-DFT calculation.

关键词： dicyanovinyl group iridium complexes absorption response dye-sensitized solar cell

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