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Mazumdar S, Torsten Clay R. Computational demonstrations of density wave of Cooper pairs and paired-electron liquid in the quarter-filled band-A brief review. CHAOS (WOODBURY, N.Y.) 2024; 34:072103. [PMID: 38990964 DOI: 10.1063/5.0200451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 06/18/2024] [Indexed: 07/13/2024]
Abstract
There has been strong interest recently in the so-called Cooper pair density wave, subsequent to the proposition that such a state occurs in the hole-doped cuprate superconductors. As of now, there is no convincing demonstration of such a state in the cuprate theoretical literature. We present here a brief but complete review of our theoretical and computational work on the paired-electron crystal (PEC), which has also been experimentally seen in the insulating phase proximate to superconductivity (SC) in organic charge-transfer solid (CTS) superconductors. Within our theory, SC in the CTS does indeed evolve from the PEC. A crucial requirement for the finding of the PEC is that the proper carrier density of one charge carrier per two sites is taken into consideration at the outset. Following the discussion of CTS superconductors, we briefly discuss how the theory can be extended to understand the phase diagram of the cuprate superconductors that has remained mysterious after nearly four decades of the discovery of SC in this family.
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Affiliation(s)
- Sumit Mazumdar
- Department of Physics, University of Arizona Tucson, Tucson, Arizona 85721, USA
| | - R Torsten Clay
- Department of Physics and Astronomy and HPC2, Center for Computational Sciences, Mississippi State University, Mississippi State, Mississippi 39762, USA
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Yamakawa H, Miyamoto T, Morimoto T, Takamura N, Liang S, Yoshimochi H, Terashige T, Kida N, Suda M, Yamamoto HM, Mori H, Miyagawa K, Kanoda K, Okamoto H. Terahertz-field-induced polar charge order in electronic-type dielectrics. Nat Commun 2021; 12:953. [PMID: 33574221 PMCID: PMC7878852 DOI: 10.1038/s41467-021-20925-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 12/29/2020] [Indexed: 11/09/2022] Open
Abstract
Ultrafast electronic-phase change in solids by light, called photoinduced phase transition, is a central issue in the field of non-equilibrium quantum physics, which has been developed very recently. In most of those phenomena, charge or spin orders in an original phase are melted by photocarrier generations, while an ordered state is usually difficult to be created from a non-ordered state by a photoexcitation. Here, we demonstrate that a strong terahertz electric-field pulse changes a Mott insulator of an organic molecular compound in κ-(ET)2Cu[N(CN)2]Cl (ET = bis(ethylenedithio)tetrathiafulvalene), to a macroscopically polarized charge-order state; herein, electronic ferroelectricity is induced by the collective intermolecular charge transfers in each dimer. In contrast, in an isostructural compound, κ-(ET)2Cu2(CN)3, which shows the spin-liquid state at low temperatures, a similar polar charge order is not stabilized by the same terahertz pulse. From the comparative studies of terahertz-field-induced second-harmonic-generation and reflectivity changes in the two compounds, we suggest the possibility that a coupling of charge and spin degrees of freedom would play important roles in the stabilization of polar charge order.
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Affiliation(s)
- H Yamakawa
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - T Miyamoto
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan.
| | - T Morimoto
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - N Takamura
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - S Liang
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - H Yoshimochi
- Department of Applied Physics, University of Tokyo, Bunkyo-Ku, 113-8656, Japan
| | - T Terashige
- AIST-UTokyo Advanced Operand-Measurement Technology Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology, Chiba, 277-8589, Japan
| | - N Kida
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan
| | - M Suda
- Division of Functional Molecular Systems, Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, Okazaki, 444-8585, Japan.,Department of Molecular Engineering, Kyoto University, Kyoto, 615-8510, Japan
| | - H M Yamamoto
- Division of Functional Molecular Systems, Research Center of Integrative Molecular Systems (CIMoS), Institute for Molecular Science, Okazaki, 444-8585, Japan
| | - H Mori
- Institute for Solid State Physics, University of Tokyo, Chiba, 277-8581, Japan
| | - K Miyagawa
- Department of Applied Physics, University of Tokyo, Bunkyo-Ku, 113-8656, Japan
| | - K Kanoda
- Department of Applied Physics, University of Tokyo, Bunkyo-Ku, 113-8656, Japan
| | - H Okamoto
- Department of Advanced Materials Science, University of Tokyo, Chiba, 277-8561, Japan. .,AIST-UTokyo Advanced Operand-Measurement Technology Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology, Chiba, 277-8589, Japan.
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Foury-Leylekian P, Ilakovac V, Fertey P, Baledent V, Milat O, Miyagawa K, Kanoda K, Hiramatsu T, Yoshida Y, Saito G, Alemany P, Canadell E, Tomic S, Pouget JP. New insights into the structural properties of κ-(BEDT-TTF) 2Ag 2(CN) 3 spin liquid. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2020; 76:581-590. [PMID: 32831277 DOI: 10.1107/s2052520620005545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 04/20/2020] [Indexed: 06/11/2023]
Abstract
Here, the first accurate study is presented of the room-temperature and 100 K structures of one of the first organic spin liquids, κ-(BEDT-TTF)2Ag2(CN)3. It is shown that the monoclinic structure determined previously is only the average one. It is shown that the exact structure presents triclinic symmetry with two non-equivalent dimers in the unit cell. But surprisingly this does not lead to a sizeable charge disproportionation between dimers. The difference from the analogue compound κ-(BEDT-TTF)2Cu2(CN)3 which also presents a spin liquid phase is discussed in detail. The data provided here show the importance of the anionic layer and in particular the transition metal position in the process of symmetry breaking. The possible impact of the symmetry breaking, albeit weak, on the spin-liquid mechanism and the influence of various disorders on the physical properties of this system is also discussed.
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Affiliation(s)
| | - Vita Ilakovac
- Sorbonne University, UPMC, LCP-MR, CNRS UMR 7614, Paris, F-75252, France
| | - Pierre Fertey
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, Gif-sur-Yvette, F-91192, France
| | - Victor Baledent
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405, Orsay, France
| | - Ognjen Milat
- Institute of Physics, Bijenička cesta 46, Zagreb, HR-10000, Croatia
| | - Kazuya Miyagawa
- Department of Applied Physics, University of Tokyo, Tokyo, 113-8656, Japan
| | - Kazushi Kanoda
- Department of Applied Physics, University of Tokyo, Tokyo, 113-8656, Japan
| | | | - Yukihiro Yoshida
- Faculty of Agriculture, Meijo University, Nagoya, 468-8502, Japan
| | - Gunzi Saito
- Faculty of Agriculture, Meijo University, Nagoya, 468-8502, Japan
| | - Pere Alemany
- Departament de Ciència de Materials i Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, Barcelona, 08028, Spain
| | - Enric Canadell
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra, 08193, Spain
| | - Silvia Tomic
- Institute of Physics, Bijenička cesta 46, Zagreb, HR-10000, Croatia
| | - Jean Paul Pouget
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405, Orsay, France
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Abstract
Abstract
Multiferroic materials, showing ordering of both electrical and magnetic degrees of freedom, are promising candidates enabling the design of novel electronic devices. Various mechanisms ranging from geometrically or spin-driven improper ferroelectricity via lone-pairs, charge-order or -transfer support multiferroicity in single-phase or composite compounds. The search for materials showing these effects constitutes one of the most important research fields in solid-state physics during the last years, but scientific interest even traces back to the middle of the past century. Especially, a potentially strong coupling between spin and electric dipoles captured the interest to control via an electric field the magnetization or via a magnetic field the electric polarization. This would imply a promising route for novel electronics. Here, we provide a review about the dielectric and ferroelectric properties of various multiferroic systems ranging from type I multiferroics, in which magnetic and ferroelectric order develop almost independently of each other, to type II multiferroics, which exhibit strong coupling of magnetic and ferroelectric ordering. We thoroughly discuss the dielectric signatures of the ferroelectric polarization for BiFeO3, Fe3O4, DyMnO3 and an organic charge-transfer salt as well as show electric-field poling studies for the hexagonal manganites and a spin-spiral system LiCuVO4.
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Yamamoto T, Fujimoto T, Naito T, Nakazawa Y, Tamura M, Yakushi K, Ikemoto Y, Moriwaki T, Kato R. Charge and Lattice Fluctuations in Molecule-Based Spin Liquids. Sci Rep 2017; 7:12930. [PMID: 29018228 PMCID: PMC5635065 DOI: 10.1038/s41598-017-13118-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 09/19/2017] [Indexed: 11/10/2022] Open
Abstract
Spin liquid (SL) systems have been the subject of much attention recently, as they have been theoretically predicted to not freeze, even at 0 K. Despite extensive searches being made for such a system, only a few candidates have been found. All of these candidates share geometrical frustrations that are based on triangular lattices. We applied vibrational spectroscopy to one of the candidates of a molecule-based SL system, and we compared its results against three antiferromagnetic compounds and four charge-ordered compounds. All of their structural motifs belong to triangular lattices. The C=C stretching modes in the SL state indicated that there were charge and lattice fluctuations. These fluctuations were suppressed but non-negligible in the AF compounds. This finding is potentially significant, as it indicates that a hidden lattice and charge fluctuation are the driving force of a geometrical frustration, which eventually leads to a SL state.
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Affiliation(s)
- Takashi Yamamoto
- Graduate School of Science and Technology, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 7908577, Japan. .,RIKEN, 2-1 Hirosawa, Wako, 3510198, Japan.
| | - Takashi Fujimoto
- Graduate School of Science and Technology, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 7908577, Japan
| | - Toshio Naito
- Graduate School of Science and Technology, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 7908577, Japan
| | - Yasuhiro Nakazawa
- Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Masafumi Tamura
- Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, 2788510, Japan
| | - Kyuya Yakushi
- Toyota Physical and Chemical Research Institute, 41-1 Yokomichi, Nagakute, 4801192, Japan
| | - Yuka Ikemoto
- JASRI, SPring-8, 1-1-1 Kouto, Sayo, Hyogo, 679-5198, Japan
| | - Taro Moriwaki
- JASRI, SPring-8, 1-1-1 Kouto, Sayo, Hyogo, 679-5198, Japan
| | - Reizo Kato
- RIKEN, 2-1 Hirosawa, Wako, 3510198, Japan
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Powell BJ, Kenny EP, Merino J. Dynamical Reduction of the Dimensionality of Exchange Interactions and the "Spin-Liquid" Phase of κ-(BEDT-TTF)_{2}X. PHYSICAL REVIEW LETTERS 2017; 119:087204. [PMID: 28952764 DOI: 10.1103/physrevlett.119.087204] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Indexed: 06/07/2023]
Abstract
We show that the anisotropy of the effective spin model for the dimer Mott insulator phase of κ-(BEDT-TTF)_{2}X salts is dramatically different from that of the underlying tight-binding model. Intradimer quantum interference results in a model of coupled spin chains, where frustrated interchain interactions suppress long-range magnetic order. Thus, we argue, the "spin liquid" phase observed in some of these materials is a remnant of the Tomonaga-Luttinger physics of a single chain. This is consistent with previous experiments and resolves some outstanding puzzles.
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Affiliation(s)
- B J Powell
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - E P Kenny
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - J Merino
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid 28049, Spain
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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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Lunkenheimer P, Müller J, Krohns S, Schrettle F, Loidl A, Hartmann B, Rommel R, de Souza M, Hotta C, Schlueter JA, Lang M. Multiferroicity in an organic charge-transfer salt that is suggestive of electric-dipole-driven magnetism. NATURE MATERIALS 2012; 11:755-758. [PMID: 22886065 DOI: 10.1038/nmat3400] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 07/13/2012] [Indexed: 06/01/2023]
Abstract
Multiferroics, showing simultaneous ordering of electrical and magnetic degrees of freedom, are remarkable materials as seen from both the academic and technological points of view. A prominent mechanism of multiferroicity is the spin-driven ferroelectricity, often found in frustrated antiferromagnets with helical spin order. There, as for conventional ferroelectrics, the electrical dipoles arise from an off-centre displacement of ions. However, recently a different mechanism, namely purely electronic ferroelectricity, where charge order breaks inversion symmetry, has attracted considerable interest. Here we provide evidence for ferroelectricity, accompanied by antiferromagnetic spin order, in a two-dimensional organic charge-transfer salt, thus representing a new class of multiferroics. We propose a charge-order-driven mechanism leading to electronic ferroelectricity in this material. Quite unexpectedly for electronic ferroelectrics, dipolar and spin order arise nearly simultaneously. This can be ascribed to the loss of spin frustration induced by the ferroelectric ordering. Hence, here the spin order is driven by the ferroelectricity, in marked contrast to the spin-driven ferroelectricity in helical magnets.
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Scriven EP, Powell BJ. Geometrical frustration in the spin liquid β'-Me3EtSb[Pd(dmit)2]2 and the valence-bond solid Me3EtP[Pd(dmit)2]2. PHYSICAL REVIEW LETTERS 2012; 109:097206. [PMID: 23002879 DOI: 10.1103/physrevlett.109.097206] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 04/02/2012] [Indexed: 06/01/2023]
Abstract
We show that the electronic structures of the title compounds predicted by density functional theory are well described by tight binding models. We determine the frustration ratio, J'/J, of the Heisenberg model on the anisotropic triangular lattice, which describes the spin degrees of freedom in the Mott insulating phase for a range of Pd(dmit)2 salts. All of the antiferromagnetic materials studied have J'/J is < or approximately equal to 0.5 or J'/J > or approximately equal to 0.9, and all salts with 0.5 < or approximately equal to J'/J < or approximately equal to 0.9 are known, experimentally, to be charge ordered valence-bond solids or spin liquids.
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Affiliation(s)
- E P Scriven
- Centre for Organic Photonics and Electronics, School of Mathematics and Physics, University of Queensland, Brisbane, Queensland 4072, Australia
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