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Deng H, Zhang J, Jeong MY, Wang D, Hu Q, Zhang S, Sereika R, Nakagawa T, Chen B, Yin X, Xiao H, Hong X, Ren J, Han MJ, Chang J, Weng H, Ding Y, Lin HQ, Mao HK. Metallization of Quantum Material GaTa 4Se 8 at High Pressure. J Phys Chem Lett 2021; 12:5601-5607. [PMID: 34110170 DOI: 10.1021/acs.jpclett.1c01069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pressure is a unique thermodynamic variable to explore the phase competitions and novel phases inaccessible at ambient conditions. The resistive switching material GaTa4Se8 displays several quantum phases under pressure, such as a Jeff = 3/2 Mott insulator, a correlated quantum magnetic metal, and d-wave topological superconductivity, which has recently drawn considerable interest. Using high-pressure Raman spectroscopy, X-ray diffraction, extended X-ray absorption, transport measurements, and theoretical calculations, we reveal a complex phase diagram for GaTa4Se8 at pressures exceeding 50 GPa. In this previously unattained pressure regime, GaTa4Se8 ranges from a Mott insulator to a metallic phase and exhibits superconducting phases. In contrast to previous studies, we unveil a hidden correlation between the structural distortion and band gap prior to the insulator-to-metal transition, and the metallic phase shows superconductivity with structural and magnetic properties that are distinctive from the lower-pressure phase. These discoveries highlight that GaTa4Se8 is a unique material to probe novel quantum phases from a structural, metallicity, magnetism, and superconductivity perspective.
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Affiliation(s)
- Hongshan Deng
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Jianbo Zhang
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Min Yong Jeong
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Dong Wang
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Qingyang Hu
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Shuai Zhang
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Raimundas Sereika
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Takeshi Nakagawa
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Bijuan Chen
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Xia Yin
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Hong Xiao
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Xinguo Hong
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Jichang Ren
- Nano and Heterogeneous Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China
| | - Myung Joon Han
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Jun Chang
- College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, People's Republic of China
| | - Hongming Weng
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Yang Ding
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - Hai-Qing Lin
- Beijing Computational Science Research Center, Beijing 100084, People's Republic of China
| | - Ho-Kwang Mao
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
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2
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Choi S, Yang J, Wang G. Emerging Memristive Artificial Synapses and Neurons for Energy-Efficient Neuromorphic Computing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2004659. [PMID: 33006204 DOI: 10.1002/adma.202004659] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/12/2020] [Indexed: 06/11/2023]
Abstract
Memristors have recently attracted significant interest due to their applicability as promising building blocks of neuromorphic computing and electronic systems. The dynamic reconfiguration of memristors, which is based on the history of applied electrical stimuli, can mimic both essential analog synaptic and neuronal functionalities. These can be utilized as the node and terminal devices in an artificial neural network. Consequently, the ability to understand, control, and utilize fundamental switching principles and various types of device architectures of the memristor is necessary for achieving memristor-based neuromorphic hardware systems. Herein, a wide range of memristors and memristive-related devices for artificial synapses and neurons is highlighted. The device structures, switching principles, and the applications of essential synaptic and neuronal functionalities are sequentially presented. Moreover, recent advances in memristive artificial neural networks and their hardware implementations are introduced along with an overview of the various learning algorithms. Finally, the main challenges of the memristive synapses and neurons toward high-performance and energy-efficient neuromorphic computing are briefly discussed. This progress report aims to be an insightful guide for the research on memristors and neuromorphic-based computing.
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Affiliation(s)
- Sanghyeon Choi
- KU-KIST Graduate School of Converging Science and Technology, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Jehyeon Yang
- KU-KIST Graduate School of Converging Science and Technology, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Gunuk Wang
- KU-KIST Graduate School of Converging Science and Technology, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
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3
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Broadband Anisotropic Optical Properties of the Terahertz Generator HMQ-TMS Organic Crystal. CONDENSED MATTER 2020. [DOI: 10.3390/condmat5030047] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
HMQ-TMS (2-(4-hydroxy-3-methoxystyryl)-1-methylquinolinium 2,4,6-trimethylbenzenesulfonate) is a recently discovered anisotropic organic crystal that can be exploited for the production of broadband high-intensity terahertz (THz) radiation through the optical rectification (OR) technique. HMQ-TMS plays a central role in THz technology due to its broad transparency range, large electro-optic coefficient and coherence length, and excellent crystal properties. However, its anisotropic optical properties have not been deeply researched yet. Here, from polarized reflectance and transmittance measurements along the x 1 and x 3 axes of a HMQ-TMS single-crystal, we extract both the refraction index n and the extinction coefficient k between 50 and 35,000 cm − 1 . We further measure the THz radiation generated by optical rectification at different infrared (IR) wavelengths and along the two x 1 and x 3 axes. These data highlight the remarkable anisotropic linear and nonlinear optical behavior of HMQ-TMS crystals, expanding the knowledge of its properties and applications from the THz to the UV region.
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Neuber E, Milde P, Butykai A, Bordacs S, Nakamura H, Waki T, Tabata Y, Geirhos K, Lunkenheimer P, Kézsmárki I, Ondrejkovic P, Hlinka J, Eng LM. Architecture of nanoscale ferroelectric domains in GaMo 4S 8. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:445402. [PMID: 30255852 DOI: 10.1088/1361-648x/aae448] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Local-probe imaging of the ferroelectric domain structure and auxiliary bulk pyroelectric measurements were conducted at low temperatures with the aim to clarify the essential aspects of the orbitally driven phase transition in GaMo4S8, a lacunar spinel crystal that can be viewed as a spin-hole analogue of its GaV4S8 counterpart. We employed multiple scanning probe techniques combined with symmetry and mechanical compatibility analysis to uncover the hierarchical domain structures, developing on the 10-100 nm scale. The identified domain architecture involves a plethora of ferroelectric domain boundaries and junctions, including primary and secondary domain walls in both electrically neutral and charged configurations, and topological line defects transforming neutral secondary walls into two oppositely charged ones.
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Affiliation(s)
- Erik Neuber
- Institute of Applied Physics, Technische Universität Dresden, D-01062 Dresden, Germany
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5
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Diener P, Janod E, Corraze B, Querré M, Adda C, Guilloux-Viry M, Cordier S, Camjayi A, Rozenberg M, Besland MP, Cario L. How a dc Electric Field Drives Mott Insulators Out of Equilibrium. PHYSICAL REVIEW LETTERS 2018; 121:016601. [PMID: 30028165 DOI: 10.1103/physrevlett.121.016601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Indexed: 06/08/2023]
Abstract
Out of equilibrium phenomena are a major issue of modern physics. In particular, correlated materials such as Mott insulators experience fascinating long-lived exotic states under a strong electric field. Yet, the origin of their destabilization by the electric field is not elucidated. Here we present a comprehensive study of the electrical response of canonical Mott insulators GaM_{4}Q_{8} (M=V, Nb, Ta, Mo; Q=S, Se) in the context of a microscopic theory of electrical breakdown where in-gap states allow for a description in terms of a two-temperature model. Our results show how the nonlinearities and the resistive transition originate from a massive creation of hot electrons under an electric field. These results give new insights for the control of the long-lived states reached under an electric field in these systems which has recently open the way to new functionalities used in neuromorphic applications.
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Affiliation(s)
- P Diener
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes Cedex 3, France
| | - E Janod
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes Cedex 3, France
| | - B Corraze
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes Cedex 3, France
| | - M Querré
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes Cedex 3, France
- Univ Rennes, CNRS, ISCR (Institut des Sciences chimiques de Rennes) UMR 6226, 35000 Rennes, France
| | - C Adda
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes Cedex 3, France
| | - M Guilloux-Viry
- Univ Rennes, CNRS, ISCR (Institut des Sciences chimiques de Rennes) UMR 6226, 35000 Rennes, France
| | - S Cordier
- Univ Rennes, CNRS, ISCR (Institut des Sciences chimiques de Rennes) UMR 6226, 35000 Rennes, France
| | - A Camjayi
- Departamento de Física, FCEyN, Universidad de Buenos Aires and IFIBA, Pabellón I, Ciudad Universitaria, 1428 CABA, Argentina
| | - M Rozenberg
- Laboratoire de Physique des Solides, Université Paris Sud, 91405 Orsay Cedex, France
| | - M P Besland
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes Cedex 3, France
| | - L Cario
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes Cedex 3, France
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6
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Direct experimental observation of the molecular J eff = 3/2 ground state in the lacunar spinel GaTa 4Se 8. Nat Commun 2017; 8:782. [PMID: 28978909 PMCID: PMC5627251 DOI: 10.1038/s41467-017-00841-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 07/28/2017] [Indexed: 11/08/2022] Open
Abstract
Strong spin–orbit coupling lifts the degeneracy of t2g orbitals in 5d transition-metal systems, leaving a Kramers doublet and quartet with effective angular momentum of Jeff = 1/2 and 3/2, respectively. These spin–orbit entangled states can host exotic quantum phases such as topological Mott state, unconventional superconductivity, and quantum spin liquid. The lacunar spinel GaTa4Se8 was theoretically predicted to form the molecular Jeff = 3/2 ground state. Experimental verification of its existence is an important first step to exploring the consequences of the Jeff = 3/2 state. Here, we report direct experimental evidence of the Jeff = 3/2 state in GaTa4Se8 by means of excitation spectra of resonant inelastic X-ray scattering at the Ta L3 and L2 edges. We find that the excitations involving the Jeff = 1/2 molecular orbital are absent only at the Ta L2 edge, manifesting the realization of the molecular Jeff = 3/2 ground state in GaTa4Se8. The strong interaction between electron spin and orbital degrees of freedom in 5d oxides can lead to exotic electronic ground states. Here the authors use resonant inelastic X-ray scattering to demonstrate that the theoretically proposed Jeff = 3/2 state is realised in GaTa4Se8.
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7
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Ruff E, Widmann S, Lunkenheimer P, Tsurkan V, Bordács S, Kézsmárki I, Loidl A. Multiferroicity and skyrmions carrying electric polarization in GaV4S8. SCIENCE ADVANCES 2015; 1:e1500916. [PMID: 26702441 PMCID: PMC4681337 DOI: 10.1126/sciadv.1500916] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 09/10/2015] [Indexed: 05/09/2023]
Abstract
Skyrmions are whirl-like topological spin objects with high potential for future magnetic data storage. A fundamental question that is relevant to both basic research and application is whether ferroelectric (FE) polarization can be associated with skyrmions' magnetic texture and whether these objects can be manipulated by electric fields. We study the interplay between magnetism and electric polarization in the lacunar spinel GaV4S8, which undergoes a structural transition associated with orbital ordering at 44 K and reveals a complex magnetic phase diagram below 13 K, including ferromagnetic, cycloidal, and Néel-type skyrmion lattice (SkL) phases. We found that the orbitally ordered phase of GaV4S8 is FE with a sizable polarization of ~1 μC/cm(2). Moreover, we observed spin-driven excess polarizations in all magnetic phases; hence, GaV4S8 hosts three different multiferroic phases with coexisting polar and magnetic order. These include the SkL phase, where we predict a strong spatial modulation of FE polarization close to the skyrmion cores. By taking into account the crystal symmetry and spin patterns of the magnetically ordered phases, we identify exchange striction as the main microscopic mechanism behind the spin-driven FE polarization in each multiferroic phase. Because GaV4S8 is unique among known SkL host materials owing to its polar crystal structure and the observed strong magnetoelectric effect, this study is an important step toward the nondissipative electric field control of skyrmions.
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Affiliation(s)
- Eugen Ruff
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg 86135, Germany
- Corresponding author. E-mail:
| | - Sebastian Widmann
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg 86135, Germany
| | - Peter Lunkenheimer
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg 86135, Germany
| | - Vladimir Tsurkan
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg 86135, Germany
- Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau MD-2028, Republic of Moldova
| | - Sandor Bordács
- Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Magneto-Optical Spectroscopy Research Group, Budapest 1111, Hungary
| | - Istvan Kézsmárki
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg 86135, Germany
- Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Magneto-Optical Spectroscopy Research Group, Budapest 1111, Hungary
| | - Alois Loidl
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg 86135, Germany
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8
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Kézsmárki I, Bordács S, Milde P, Neuber E, Eng LM, White JS, Rønnow HM, Dewhurst CD, Mochizuki M, Yanai K, Nakamura H, Ehlers D, Tsurkan V, Loidl A. Néel-type skyrmion lattice with confined orientation in the polar magnetic semiconductor GaV4S8. NATURE MATERIALS 2015; 14:1116-1122. [PMID: 26343913 DOI: 10.1038/nmat4402] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 07/21/2015] [Indexed: 06/05/2023]
Abstract
Following the early prediction of the skyrmion lattice (SkL)--a periodic array of spin vortices--it has been observed recently in various magnetic crystals mostly with chiral structure. Although non-chiral but polar crystals with Cnv symmetry were identified as ideal SkL hosts in pioneering theoretical studies, this archetype of SkL has remained experimentally unexplored. Here, we report the discovery of a SkL in the polar magnetic semiconductor GaV4S8 with rhombohedral (C3v) symmetry and easy axis anisotropy. The SkL exists over an unusually broad temperature range compared with other bulk crystals and the orientation of the vortices is not controlled by the external magnetic field, but instead confined to the magnetic easy axis. Supporting theory attributes these unique features to a new Néel-type of SkL describable as a superposition of spin cycloids in contrast to the Bloch-type SkL in chiral magnets described in terms of spin helices.
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Affiliation(s)
- I Kézsmárki
- Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Magneto-optical Spectroscopy Research Group, 1111 Budapest, Hungary
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
| | - S Bordács
- Department of Physics, Budapest University of Technology and Economics and MTA-BME Lendület Magneto-optical Spectroscopy Research Group, 1111 Budapest, Hungary
| | - P Milde
- Institut für Angewandte Photophysik, TU Dresden, D-01069 Dresden, Germany
| | - E Neuber
- Institut für Angewandte Photophysik, TU Dresden, D-01069 Dresden, Germany
| | - L M Eng
- Institut für Angewandte Photophysik, TU Dresden, D-01069 Dresden, Germany
| | - J S White
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - H M Rønnow
- Laboratory for Quantum Magnetism, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - C D Dewhurst
- Institut Laue-Langevin, 6 rue Jules Horowitz 38042 Grenoble, France
| | - M Mochizuki
- Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - K Yanai
- Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558, Japan
| | - H Nakamura
- Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501, Japan
| | - D Ehlers
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
| | - V Tsurkan
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
- Institute of Applied Physics, Academy of Sciences of Moldova, MD 2028, Chisinau, Republica Moldova
| | - A Loidl
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany
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9
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Singh K, Simon C, Cannuccia E, Lepetit MB, Corraze B, Janod E, Cario L. Orbital-ordering-driven multiferroicity and magnetoelectric coupling in GeV₄S₈. PHYSICAL REVIEW LETTERS 2014; 113:137602. [PMID: 25302917 DOI: 10.1103/physrevlett.113.137602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Indexed: 06/04/2023]
Abstract
We report here the discovery of multiferroicity and large magnetoelectric coupling in the type I orbital order system GeV₄S₈. Our study demonstrates that this clustered compound displays a para-ferroelectric transition at 32 K. This transition originates from an orbital ordering which reorganizes the charge within the transition metal clusters. Below the antiferromagnetic transition at 17 K, the application of a magnetic field significantly affects the ferroelectric polarization, revealing thus a large magnetoelectric coupling. Our study suggests that the application of a magnetic field induces a metamagnetic transition which significantly affects the ferroelectric polarization thanks to an exchange striction phenomenon.
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Affiliation(s)
- Kiran Singh
- Laboratoire CRISMAT, CNRS UMR 6508, ENSICAEN, 6 Bd. du Maréchal Juin, 14050 Caen Cedex 4, France
| | - Charles Simon
- Laboratoire CRISMAT, CNRS UMR 6508, ENSICAEN, 6 Bd. du Maréchal Juin, 14050 Caen Cedex 4, France and Institut Laue Langevin, 71 avenue des Martyrs, 38000 Grenoble, France
| | - Elena Cannuccia
- Institut Laue Langevin, 71 avenue des Martyrs, 38000 Grenoble, France
| | - Marie-Bernadette Lepetit
- Institut Laue Langevin, 71 avenue des Martyrs, 38000 Grenoble, France and Institut Néel, CNRS UPR 2940 Département MCBT, 25 avenue des Martyrs, BP 166, 38042 Grenoble Cedex 9, France
| | - Benoit Corraze
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la houssinière, BP32229, 44322 Nantes Cedex 3, France
| | - Etienne Janod
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la houssinière, BP32229, 44322 Nantes Cedex 3, France
| | - Laurent Cario
- Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la houssinière, BP32229, 44322 Nantes Cedex 3, France
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10
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Camjayi A, Acha C, Weht R, Rodríguez MG, Corraze B, Janod E, Cario L, Rozenberg MJ. First-order insulator-to-metal Mott transition in the paramagnetic 3D system GaTa4Se8. PHYSICAL REVIEW LETTERS 2014; 113:086404. [PMID: 25192113 DOI: 10.1103/physrevlett.113.086404] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Indexed: 06/03/2023]
Abstract
The nature of the Mott transition in the absence of any symmetry breaking remains a matter of debate. We study the correlation-driven insulator-to-metal transition in the prototypical 3D Mott system GaTa(4)Se(8), as a function of temperature and applied pressure. We report novel experiments on single crystals, which demonstrate that the transition is of first order and follows from the coexistence of two states, one insulating and one metallic, that we toggle with a small bias current. We provide support for our findings by contrasting the experimental data with calculations that combine local density approximation with dynamical mean-field theory, which are in very good agreement.
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Affiliation(s)
- A Camjayi
- Departamento de Física, FCEN, UBA, and IFIBA, CONICET, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | - C Acha
- Departamento de Física, FCEN, UBA, and IFIBA, CONICET, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | - R Weht
- Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (CNEA), Avenida General Paz y Constituyentes, 1650 San Martín, Argentina and Instituto Sábato, Universidad Nacional de San Martín-CNEA, 1650 San Martín, Argentina
| | - M G Rodríguez
- Departamento de Física, FCEN, UBA, and IFIBA, CONICET, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires, Argentina
| | - B Corraze
- Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes, France
| | - E Janod
- Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes, France
| | - L Cario
- Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes, France
| | - M J Rozenberg
- Laboratoire de Physique des Solides, CNRS-UMR8502, Université de Paris-Sud, Orsay 91405, France
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11
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Spin-orbital entangled molecular jeff states in lacunar spinel compounds. Nat Commun 2014; 5:3988. [PMID: 24889209 DOI: 10.1038/ncomms4988] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 04/29/2014] [Indexed: 11/08/2022] Open
Abstract
The entanglement of the spin and orbital degrees of freedom through the spin-orbit coupling has been actively studied in condensed matter physics. In several iridium oxide systems, the spin-orbital entangled state, identified by the effective angular momentum jeff, can host novel quantum phases. Here we show that a series of lacunar spinel compounds, GaM4X8 (M=Nb, Mo, Ta and W and X=S, Se and Te), gives rise to a molecular jeff state as a new spin-orbital composite on which the low-energy effective Hamiltonian is based. A wide range of electron correlations is accessible by tuning the bandwidth under external and/or chemical pressure, enabling us to investigate the cooperation between spin-orbit coupling and electron correlations. As illustrative examples, a two-dimensional topological insulating phase and an anisotropic spin Hamiltonian are investigated in the weak and strong coupling regimes, respectively. Our finding can provide an ideal platform for exploring jeff physics and the resulting emergent phenomena.
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12
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Dubost V, Cren T, Vaju C, Cario L, Corraze B, Janod E, Debontridder F, Roditchev D. Resistive switching at the nanoscale in the Mott insulator compound GaTa4Se8. NANO LETTERS 2013; 13:3648-3653. [PMID: 23826620 DOI: 10.1021/nl401510p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We study the Mott insulator compound GaTa4Se8 in which we previously discovered an electric-field-induced resistive transition. We show that the resistive switching is associated to the appearance of metallic and super-insulating nanodomains by means of scanning tunneling microscopy/spectroscopy (STM/STS). Moreover, we show that local electronic transitions can be controlled at the nanoscale at room temperature using the electric field of the STM tip. This opens the way for possible applications in resistive random access memories (RRAM) devices.
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Affiliation(s)
- Vincent Dubost
- Institut des Nanosciences de Paris, Université Pierre et Marie Curie, CNRS UMR 7588, Paris, France
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13
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Stoliar P, Cario L, Janod E, Corraze B, Guillot-Deudon C, Salmon-Bourmand S, Guiot V, Tranchant J, Rozenberg M. Universal electric-field-driven resistive transition in narrow-gap Mott insulators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:3222-3226. [PMID: 23649904 DOI: 10.1002/adma.201301113] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Indexed: 06/02/2023]
Abstract
A striking universality in the electric-field-driven resistive switching is shown in three prototypical narrow-gap Mott systems. This model, based on key theoretical features of the Mott phenomenon, reproduces the general behavior of this resistive switching and demonstrates that it can be associated with a dynamically directed avalanche. This model predicts non-trivial accumulation and relaxation times that are verified experimentally.
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Affiliation(s)
- Pablo Stoliar
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris Sud, Bât 510, 91405 Orsay, France.
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14
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Avalanche breakdown in GaTa4Se8−xTex narrow-gap Mott insulators. Nat Commun 2013; 4:1722. [DOI: 10.1038/ncomms2735] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 03/14/2013] [Indexed: 11/08/2022] Open
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