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Urai M, Miyagawa K, Watanabe Y, Zhilyaeva EI, Torunova SA, Lyubovskaya RN, Drichko N, Kanoda K. Anomalously field-susceptible spin clusters emerging in the electric-dipole liquid candidate κ-(ET) 2Hg(SCN) 2Br. SCIENCE ADVANCES 2022; 8:eabn1680. [PMID: 36542712 PMCID: PMC9771449 DOI: 10.1126/sciadv.abn1680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Mutual interactions in many-body systems bring about various exotic phases, among which liquid-like states failing to order due to frustration are of keen interest. The organic system with an anisotropic triangular lattice of molecular dimers, κ-(ET)2Hg(SCN)2Br, has been suggested to host a dipole liquid arising from intradimer charge-imbalance instability, possibly offering an unprecedented stage for the spin degrees of freedom. Here, we show that an extraordinary unordered/unfrozen spin state having soft matter-like spatiotemporal characteristics emerges in this system. 1H nuclear magnetic resonance (NMR) spectra and magnetization measurements indicate that gigantic, staggered moments are nonlinearly and inhomogeneously induced by a magnetic field, whereas the moments vanish in the zero-field limit. The analysis of the NMR relaxation rate signifies that the moments fluctuate at a characteristic frequency slowing down to below megahertz at low temperatures. The inhomogeneity, local correlation, and slow dynamics indicative of middle-scale dynamical correlation length of several nanometers suggest novel frustration-driven spin clusterization.
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Affiliation(s)
- Mizuki Urai
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Kazuya Miyagawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Yuta Watanabe
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Elena I. Zhilyaeva
- Institute of Problems of Chemical Physics RAS, 142432 Chernogolovka, Russia
| | | | | | - Natalia Drichko
- The Institute for Quantum Matter and the Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
- The Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Kazushi Kanoda
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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2
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Olejniczak I, Barszcz B, Auban-Senzier P, Jeschke HO, Wojciechowski R, Schlueter JA. Charge-Ordering and Structural Transition in the New Organic Conductor δ'-(BEDT-TTF) 2CF 3CF 2SO 3. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:1890-1900. [PMID: 35145572 PMCID: PMC8819691 DOI: 10.1021/acs.jpcc.1c09458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/11/2022] [Indexed: 06/14/2023]
Abstract
We report structural, transport, and optical properties and electronic structure calculations of the δ'-(BEDT-TTF)2CF3CF2SO3 (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) organic conductor that has been synthesized by electrocrystallization. Electronic structure calculations demonstrate the quasi-one-dimensional Fermi surfaces of the compound, while the optical spectra are characteristic for a dimer-Mott insulator. The single-crystal X-ray diffraction measurements reveal the structural phase transition at 200 K from the ambient-temperature monoclinic P21/m phase to the low-temperature orthorhombic Pca21 phase, while the resistivity measurements clearly show the first order semiconductor-semiconductor transition at the same temperature. This transition is accompanied by charge-ordering as it is confirmed by splitting of charge-sensitive vibrational modes observed in the Raman and infrared spectra. The horizontal stripe charge-order pattern is suggested based on the crystal structure, band structure calculations, and optical spectra.
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Affiliation(s)
- Iwona Olejniczak
- Institute
of Molecular Physics, Polish Academy of
Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Bolesław Barszcz
- Institute
of Molecular Physics, Polish Academy of
Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Pascale Auban-Senzier
- Laboratoire
de Physique des Solides, Université Paris-Saclay, UMR 8502
CNRS, Université Paris-Sud, Orsay 91405, France
| | - Harald O. Jeschke
- Research
Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Roman Wojciechowski
- Department
of Molecular Physics, Faculty of Chemistry, Technical University of Łódź, Żeromskiego 116, 90-924 Łódź, Poland
| | - John A. Schlueter
- Materials
Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
- Division
of Materials Research, National Science
Foundation, 2415 Eisenhower
Avenue, Alexandria, Virginia 22314, United States
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3
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Makinde ZO, van der Heijden NJ, Clyde D, Nam S, Brothers PJ, Malmström J, Granville S, Domigan LJ, McGillivray DJ, Williams DE. Geometric Frustration and Long-Range Ordering Induced by Surface Pressure Oscillation in a Langmuir-Blodgett Monolayer of Magnetic Soft Spheres. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10150-10158. [PMID: 34384020 DOI: 10.1021/acs.langmuir.1c01577] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
As a step toward the bottom-up construction of magnonic systems, this paper demonstrates the use of a large-amplitude surface-pressure annealing technique to generate 2-D order in a Langmuir-Blodgett monolayer of magnetic soft spheres comprising a surfactant-encapsulated polyoxometalate. The films show a distorted square lattice interpreted as due to geometric frustration caused by 2-D confinement between soft walls, one being the air interface and the other the aqueous subphase. Hysteresis and relaxation phenomena in the 2-D layers are suggested to be due to folding and time-dependent interpenetration of surfactant chains.
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Affiliation(s)
- Zainab O Makinde
- School of Chemical Sciences, The University of Auckland, 23 Symonds St., Auckland 1010, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
| | - Nadine J van der Heijden
- School of Chemical Sciences, The University of Auckland, 23 Symonds St., Auckland 1010, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
| | - Daniel Clyde
- School of Chemical Sciences, The University of Auckland, 23 Symonds St., Auckland 1010, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
| | - Seong Nam
- School of Chemical Sciences, The University of Auckland, 23 Symonds St., Auckland 1010, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
| | - Penelope J Brothers
- School of Chemical Sciences, The University of Auckland, 23 Symonds St., Auckland 1010, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
- Research School of Chemistry, The Australian National University, Canberra ACT 2601, Australia
| | - Jenny Malmström
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
- Department of Chemical and Materials Engineering, The University of Auckland, 20 Symonds St., Auckland 1010, New Zealand
| | - Simon Granville
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
- Robinson Research Institute, Victoria University of Wellington, Wellington 6140, New Zealand
| | - Laura J Domigan
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
- Department of Chemical and Materials Engineering, The University of Auckland, 20 Symonds St., Auckland 1010, New Zealand
| | - Duncan J McGillivray
- School of Chemical Sciences, The University of Auckland, 23 Symonds St., Auckland 1010, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
| | - David E Williams
- School of Chemical Sciences, The University of Auckland, 23 Symonds St., Auckland 1010, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, Wellington 6140, New Zealand
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4
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Correlated insulating states at fractional fillings of moiré superlattices. Nature 2020; 587:214-218. [PMID: 33177668 DOI: 10.1038/s41586-020-2868-6] [Citation(s) in RCA: 153] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 09/03/2020] [Indexed: 11/08/2022]
Abstract
Quantum particles on a lattice with competing long-range interactions are ubiquitous in physics; transition metal oxides1,2, layered molecular crystals3 and trapped-ion arrays4 are a few examples. In the strongly interacting regime, these systems often show a rich variety of quantum many-body ground states that challenge theory2. The emergence of transition metal dichalcogenide moiré superlattices provides a highly controllable platform in which to study long-range electronic correlations5-12. Here we report an observation of nearly two dozen correlated insulating states at fractional fillings of tungsten diselenide/tungsten disulfide moiré superlattices. This finding is enabled by a new optical sensing technique that is based on the sensitivity to the dielectric environment of the exciton excited states in a single-layer semiconductor of tungsten diselenide. The cascade of insulating states shows an energy ordering that is nearly symmetric about a filling factor of half a particle per superlattice site. We propose a series of charge-ordered states at commensurate filling fractions that range from generalized Wigner crystals7 to charge density waves. Our study lays the groundwork for using moiré superlattices to simulate a wealth of quantum many-body problems that are described by the two-dimensional extended Hubbard model3,13,14 or spin models with long-range charge-charge and exchange interactions15,16.
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5
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Matsuura M, Sasaki T, Iguchi S, Gati E, Müller J, Stockert O, Piovano A, Böhm M, Park JT, Biswas S, Winter SM, Valentí R, Nakao A, Lang M. Lattice Dynamics Coupled to Charge and Spin Degrees of Freedom in the Molecular Dimer-Mott Insulator κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Cl. PHYSICAL REVIEW LETTERS 2019; 123:027601. [PMID: 31386497 DOI: 10.1103/physrevlett.123.027601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 05/24/2019] [Indexed: 06/10/2023]
Abstract
Inelastic neutron scattering measurements on the molecular dimer-Mott insulator κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Cl reveal a phonon anomaly in a wide temperature range. Starting from T_{ins}∼50-60 K where the charge gap opens, the low-lying optical phonon modes become overdamped upon cooling towards the antiferromagnetic ordering temperature T_{N}=27 K, where also a ferroelectric ordering at T_{FE}≈T_{N} occurs. Conversely, the phonon damping becomes small again when spins and charges are ordered below T_{N}, while no change of the lattice symmetry is observed across T_{N} in neutron diffraction measurements. We assign the phonon anomalies to structural fluctuations coupled to charge and spin degrees of freedom in the BEDT-TTF molecules.
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Affiliation(s)
- Masato Matsuura
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
| | - Takahiko Sasaki
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Satoshi Iguchi
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Elena Gati
- Institute of Physics, Goethe-University Frankfurt, 60438 Frankfurt (M), Germany
| | - Jens Müller
- Institute of Physics, Goethe-University Frankfurt, 60438 Frankfurt (M), Germany
| | - Oliver Stockert
- Max-Planck-Institut für Chemische Physik fester Stoffe, D-01187 Dresden, Germany
| | - Andrea Piovano
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Martin Böhm
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Jitae T Park
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching, Germany
| | - Sananda Biswas
- Institute for Theoretical Physics, Goethe-University Frankfurt, 60438 Frankfurt (M), Germany
| | - Stephen M Winter
- Institute for Theoretical Physics, Goethe-University Frankfurt, 60438 Frankfurt (M), Germany
| | - Roser Valentí
- Institute for Theoretical Physics, Goethe-University Frankfurt, 60438 Frankfurt (M), Germany
| | - Akiko Nakao
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
| | - Michael Lang
- Institute of Physics, Goethe-University Frankfurt, 60438 Frankfurt (M), Germany
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6
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Pustogow A, Bories M, Löhle A, Rösslhuber R, Zhukova E, Gorshunov B, Tomić S, Schlueter JA, Hübner R, Hiramatsu T, Yoshida Y, Saito G, Kato R, Lee TH, Dobrosavljević V, Fratini S, Dressel M. Quantum spin liquids unveil the genuine Mott state. NATURE MATERIALS 2018; 17:773-777. [PMID: 30082905 DOI: 10.1038/s41563-018-0140-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 06/26/2018] [Indexed: 05/13/2023]
Abstract
The localization of charge carriers by electronic repulsion was suggested by Mott in the 1930s to explain the insulating state observed in supposedly metallic NiO. The Mott metal-insulator transition has been subject of intense investigations ever since1-3-not least for its relation to high-temperature superconductivity4. A detailed comparison to real materials, however, is lacking because the pristine Mott state is commonly obscured by antiferromagnetism and a complicated band structure. Here we study organic quantum spin liquids, prototype realizations of the single-band Hubbard model in the absence of magnetic order. Mapping the Hubbard bands by optical spectroscopy provides an absolute measure of the interaction strength and bandwidth-the crucial parameters that enter calculations. In this way, we advance beyond conventional temperature-pressure plots and quantitatively compose a generic phase diagram for all genuine Mott insulators based on the absolute strength of the electronic correlations. We also identify metallic quantum fluctuations as a precursor of the Mott insulator-metal transition, previously predicted but never observed. Our results suggest that all relevant phenomena in the phase diagram scale with the Coulomb repulsion U, which provides a direct link to unconventional superconductivity in cuprates and other strongly correlated materials.
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Affiliation(s)
- A Pustogow
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany.
| | - M Bories
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
| | - A Löhle
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
| | - R Rösslhuber
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
| | - E Zhukova
- Moscow Institute of Physics and Technology (State University), Dolgoprudny, Russia
| | - B Gorshunov
- Moscow Institute of Physics and Technology (State University), Dolgoprudny, Russia
| | - S Tomić
- Institut za fiziku, Zagreb, Croatia
| | - J A Schlueter
- Division of Materials Research, National Science Foundation, Arlington, VA, USA
- Materials Science Division, Argonne National Laboratory, Argonne, IL, USA
| | - R Hübner
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
- Biomedizinische Chemie, Institut für Klinische Radiologie und Nuklearmedizin, Universität Heidelberg, Mannheim, Germany
| | - T Hiramatsu
- Faculty of Agriculture, Meijo University, Nagoya, Japan
| | - Y Yoshida
- Faculty of Agriculture, Meijo University, Nagoya, Japan
- Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - G Saito
- Faculty of Agriculture, Meijo University, Nagoya, Japan
- Toyota Physical and Chemical Research Institute, Nagakute, Japan
| | - R Kato
- Condensed Molecular Materials Laboratory, RIKEN, Wako-shi, Saitama, Japan
| | - T-H Lee
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - V Dobrosavljević
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - S Fratini
- Institut Néel - CNRS and Université Grenoble Alpes, Grenoble, France
| | - M Dressel
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
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7
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8
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9
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Ikeuchi Y, Takatsu H, Tassel C, Goto Y, Murakami T, Kageyama H. High‐Pressure Synthesis of Fully Occupied Tetragonal and Cubic Tungsten Bronze Oxides. Angew Chem Int Ed Engl 2017; 56:5770-5773. [DOI: 10.1002/anie.201701732] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Yuya Ikeuchi
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Hiroshi Takatsu
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Cédric Tassel
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Yoshihiro Goto
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Taito Murakami
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Hiroshi Kageyama
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
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10
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Ikeuchi Y, Takatsu H, Tassel C, Goto Y, Murakami T, Kageyama H. High‐Pressure Synthesis of Fully Occupied Tetragonal and Cubic Tungsten Bronze Oxides. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201701732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yuya Ikeuchi
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Hiroshi Takatsu
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Cédric Tassel
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Yoshihiro Goto
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Taito Murakami
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
| | - Hiroshi Kageyama
- Graduate School of Engineering Kyoto University Kyoto 615-8510 Japan
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11
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Löhle A, Rose E, Singh S, Beyer R, Tafra E, Ivek T, Zhilyaeva EI, Lyubovskaya RN, Dressel M. Pressure dependence of the metal-insulator transition in κ-(BEDT-TTF) 2Hg(SCN) 2Cl: optical and transport studies. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:055601. [PMID: 27958198 DOI: 10.1088/1361-648x/29/5/055601] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The two-dimensional organic conductor κ-(BEDT-TTF)2-Hg(SCN)2Cl exhibits a pronounced metal-insulator transition at [Formula: see text] K. From the splitting of the molecular vibrations, the phase transition can be unambiguously assigned to charge-ordering with [Formula: see text]. We have investigated the pressure evolution of this behavior by temperature-dependent electrical transport measurements and optical investigations applying hydrostatic pressure up to 12 kbar. The data reveal a mean-field like down-shift of [Formula: see text] with a critical pressure of [Formula: see text] kbar and a metallic state above the suppression of the charge-ordered state; no traces of superconductivity could be identified down to T = 1.5 K. As the charge order [Formula: see text] sets in abruptly with decreasing temperature, its size remains unaffected by pressure. However, the fraction of charge imbalanced molecules decreases until it is completely absent above 1.6 kbar.
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Affiliation(s)
- A Löhle
- Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany
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12
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Ishihara S. Electronic ferroelectricity in molecular organic crystals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:493201. [PMID: 25398158 DOI: 10.1088/0953-8984/26/49/493201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Electronic ferroelectricity in molecular organic crystals is reviewed from a theoretical perspective. In particular, we focus on the charge-driven-type electronic ferroelectricity where electronic charge order without inversion symmetry induces a spontaneous electric polarization in quarter-filling systems. Two necessary conditions to realize this type of ferroelectricity are the dimer-type lattice structure and alternate electronic charge alignments. Some prototypical organic compounds are introduced. In particular, κ-type BEDT-TTF organic salts, which are termed the dimer-Mott insulating systems, are focused on. Recent developments in the theoretical researches for dielectric and magnetodielectric properties, a collective dipole excitation and a possibility of superconductivity induced by polar charge fluctuation are reviewed. Some perspectives are presented.
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Affiliation(s)
- Sumio Ishihara
- Department of Physics, Tohoku University, Sendai 980-8578, Japan CREST, Sendai 980-8578, Japan
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13
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Okazaki R, Ikemoto Y, Moriwaki T, Shikama T, Takahashi K, Mori H, Nakaya H, Sasaki T, Yasui Y, Terasaki I. Optical conductivity measurement of a dimer Mott-insulator to charge-order phase transition in a two-dimensional quarter-filled organic salt compound. PHYSICAL REVIEW LETTERS 2013; 111:217801. [PMID: 24313527 DOI: 10.1103/physrevlett.111.217801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 08/12/2013] [Indexed: 06/02/2023]
Abstract
We report a novel insulator-insulator transition arising from the internal charge degrees of freedom in the two-dimensional quarter-filled organic salt β-(meso-DMBEDT-TTF)2PF6. The optical conductivity spectra above Tc=70 K display a prominent feature of the dimer Mott insulator, characterized by a substantial growth of a dimer peak near 0.6 eV with decreasing temperature. The dimer peak growth is rapidly quenched as soon as a peak of the charge order appears below Tc, indicating a competition between the two insulating phases. Our infrared imaging spectroscopy has further revealed a spatially competitive electronic phase far below Tc, suggesting a nature of quantum phase transition driven by material-parameter variations.
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Affiliation(s)
- Ryuji Okazaki
- Department of Physics, Nagoya University, Nagoya 464-8602, Japan
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14
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Tomić S, Pinterić M, Ivek T, Sedlmeier K, Beyer R, Wu D, Schlueter JA, Schweitzer D, Dressel M. Magnetic ordering and charge dynamics in κ-(BEDT-TTF)2Cu[N(CN)2]Cl. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:436004. [PMID: 24107640 DOI: 10.1088/0953-8984/25/43/436004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The Mott insulator κ-(BEDT-TTF)2Cu[N(CN)2]Cl consists of molecular dimers arranged on an anisotropic triangular lattice. At low temperatures a pronounced dielectric anomaly is observed, and eventually a canted antiferromagnetic ground state forms. Optical spectroscopy clearly rules out charge imbalance and the existence of quantum electric dipoles with a dipolar-spin coupling. Here we suggest a novel form of spin-charge coupling where the prominent in-plane dielectric response in κ-(BEDT-TTF)2Cu[N(CN)2]Cl is explained by short-range discommensurations of the antiferromagnetic phase in the temperature range 30 K < T < 50 K, and by relaxation of charged domain walls in the ferromagnetic structure at lower temperatures.
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Affiliation(s)
- S Tomić
- Institut za fiziku, PO Box 304, HR-10001 Zagreb, Croatia
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15
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Łapiński A, Świetlik R, Ouahab L, Golhen S. Spectroscopic Studies of the Phase Transition from the Mott Insulator State to the Charge-Ordering State of κ-(ET)4[M(CN)6][N(C2H5)4]·2H2O (M = CoIII and FeIII) Salts. J Phys Chem A 2013; 117:5241-50. [DOI: 10.1021/jp402027x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrzej Łapiński
- Institute of Molecular Physics, Polish Academy of Sciences, ul. Mariana Smoluchowskiego
17, 60-179 Poznań, Poland
| | - Roman Świetlik
- Institute of Molecular Physics, Polish Academy of Sciences, ul. Mariana Smoluchowskiego
17, 60-179 Poznań, Poland
| | - Lahcène Ouahab
- Organométalliques: Matériaux
et Catalyse UMR 6226 CNRS-UR1 Institut des Sciences Chimiques de Rennes, Université de Rennes 1, 35042, Rennes Cedex,
France
| | - Stéphane Golhen
- Organométalliques: Matériaux
et Catalyse UMR 6226 CNRS-UR1 Institut des Sciences Chimiques de Rennes, Université de Rennes 1, 35042, Rennes Cedex,
France
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