High-Pressure Study up to 9.9 GPa of Organic Mott Insulator, β'-(BEDT-TTF)<sub>2</sub>AuCl<sub>2</sub>

Taniguchi, Hiromi; Miyashita, M.; Uchiyama, Kenichi; Sato, Ryosuke; Ishii, Yasuyuki; Satoh, Kazuhiko; Môri, N.; Hedo, Masato; Uwatoko, Yoshiya

doi:10.1143/jpsj.74.1370

Cited by 11 publications

(5 citation statements)

References 14 publications

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“…Here, we note the absence of the superconductivity under pressures up to 9.9 GPa in the organic Mott insulator β -(BEDT-TTF) 2 AuCl 2 . It has a crystal structure similar to that of β -(BEDT-TTF) 2 ICl 2 , which has the highest T c among organics at ∼8 GPa [72]. The reason for the contrasting behavior was discussed in terms of the difference in the anion size: In the β -type family, the small anion enhances the electronic dimerization of BEDT-TTF donor through the structural interaction between the anions and BEDT-TTF molecules under pressure, leading to the increase in U /W and the suppression of superconducting phase.…”

Section: (Tmttf) 2 X : New Aspect Of Unified T-p Phase Diagrammentioning

confidence: 98%

Recent progress in high-pressure studies on organic conductors

Yasuzuka

Murata

2009

Science and Technology of Advanced Materials

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Recent high-pressure studies of organic conductors and superconductors are reviewed. The discovery of the highest T c superconductivity among organics under high pressure has triggered the further progress of the high-pressure research. Owing to this finding, various organic conductors with the strong electron correlation were investigated under high pressures. This review includes the pressure techniques using the cubic anvil apparatus, as well as high-pressure studies of the organic conductors up to 10 GPa showing extraordinary temperature and pressure dependent transport phenomena.

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Section: (Tmttf) 2 X : New Aspect Of Unified T-p Phase Diagrammentioning

confidence: 98%

Recent progress in high-pressure studies on organic conductors

Yasuzuka

Murata

2009

Science and Technology of Advanced Materials

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“…This behavior is seen even in other organic conductors. 20,21) Probably, the small humps are caused by the friction between a pyrophyllite gasket and WC anvils.…”

Section: Methodsmentioning

confidence: 99%

Metallization of the Organic Conductor (TTM-TTP)I₃with a Highly One-Dimensional Half-Filled Band under Pressure beyond 7 GPa

et al. 2007

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It is theoretically predicted that the ground state of the one-dimensional (1D) half-filled system is the Mott insulator at any positive on-site Coulomb interaction U . In this paper, we demonstrate that (TTM-TTP)I3 with a highly 1D half-filled energy band is almost metallized by the application of pressure beyond 7 GPa. We find that the metal-insulator transition temperature decreases linearly with increasing pressure and is directing towards 0 K near 10 GPa. Above 5.7 GPa, the metallic behaviors are observed in the high-temperature region for 70 < T < 300 K, in which the temperature dependence of the resistivity is described by ρ(T ) ∝ T α with α ∼ 0.3. The nature of the metallic state is discussed in terms of the Tomonaga-Luttinger liquid described by the Hubbard model. KEYWORDS: (TTM-TTP)I3, organic conductor, one-dimensional system, half-filling, high-pressure, Tomonaga-Luttinger liquid, Hubbard model, Kρ IntroductionMetal-insulator (MI) transitions by Coulomb interaction are accompanied with huge resistance change and are widely observed in strongly correlated systems. Many theories of strongly correlated systems begin with a Hubbard model because of its simplicity.1) The Hubbard model is the prototypical model used for the description of correlated fermions in a variety of materials, ranging from high-T c superconductors to heavy fermion compounds and organic molecular crystals. In spite of its apparent simplicity, there is still no general solution, or even a consensus on its fundamental properties for the Hubbard model. Notable exceptions are the cases of oneand infinite-dimensions.2, 3) In one-dimension, an exact solution is available.4) Especially, the one-dimensional (1D) half-filled case is special but important because it corresponds to the strong coupling limit of the Hubbard model, i.e., U → ∞. 5) That is, no matter how small U is, the ground state is the Mott insulator. Thus metallization of the 1D half-filled system is one of the most challenging problems in the strongly correlated electronic systems.In this paper, we report the metallization of (TTM-TTP)I 3 with a highly 1D half-filled band, 6) where TTM-TTP stands for 2,5-bis[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiapentalene [see Fig. 1(a)]. 7,8) In the interchain directions, the TTM-TTP molecules cannot approach close to each other because of the steric hindrance of the terminal -SCH 3 groups.7) According to the band structure calculation, the interchain interactions, t a , t b (< 0.01 eV) are less than 1/20 of the intrachain interaction, t c = 0.26 eV, which is much more onedimensional than the typical quasi-1D Bechgaard salts.

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“…The ground state at ambient pressure is AFM with T N =22 K [378]. The related salt β -(ET) 2 AuCl 2 has a slightly higher T N =28 K with however no SC reported in pressures up to 9.9 GPa [347,348]. The AFM moment in the AFM state of ICl 2 is large, approximately 1.0 µ B per dimer [379].…”

Section: β β and β Type Ctsmentioning

confidence: 98%

From charge- and spin-ordering to superconductivity in the organic charge-transfer solids

Clay,

Mazumdar

2018

Preprint

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We review recent progress in understanding the different spatial broken symmetries that occur in the normal states of the family of charge-transfer solids (CTS) that exhibit superconductivity (SC), and discuss how this knowledge gives insight to the mechanism of the unconventional SC in these systems. A great variety of spatial broken symmetries occur in the semiconducting states proximate to SC in the CTS, including charge ordering, antiferromagnetism and spin-density wave, spin-Peierls state and the quantum spin liquid. We show that a unified theory of the diverse broken symmetry states necessarily requires explicit incorporation of strong electron-electron interactions and lattice discreteness, and most importantly, the correct bandfilling of one-quarter, as opposed to the effective half-filled band picture that is often employed. Uniquely in the quarter-filled band, there is a very strong tendency to form nearest neighbor spin-singlets, in both one-and two-dimension. The spin-singlet in the quarter-filled band is necessarily charge-disproportionated, with charge-rich pairs of nearest neighbor sites separated by charge-poor pairs of sites in the insulating state. Thus the tendency to spin-singlets, a quantum effect, drives a commensurate charge-order in the correlated quarter-filled band. This charge-ordered spin-singlet, which we label as a paired-electron crystal (PEC), is different from and competes with both the antiferromagnetic (AFM) state and the Wigner crystal (WC) of single electrons. Further, unlike these classical broken symmetries, the PEC is characterized by a spin gap. The tendency to the PEC in two dimension is enhanced by lattice frustration. The concept of the PEC mirrors parallel development of the idea of a density wave of Cooper pairs in the superconducting high T c cuprates, where also the existence of a charge-ordered state in between the antiferromagnetic and the superconducting phase has now been confirmed. Following this characterization of the spatial broken symmetries, we critically reexamine spin-fluctuation and resonating valence bond theories of frustration-driven SC within half-filled band Hubbard and Hubbard-Heisenberg Hamiltonians for the superconducting CTS. We present numerical evidence for the absence of SC within the half-filled band correlated-electron Hamiltonians for any degree of frustration. We then develop a valence-bond theory of SC within which the superconducting state is reached by the destabilization of the PEC by additional pressure-induced lattice frustration that makes the spin-singlets mobile. We present limited but accurate numerical evidence for the existence of such a charge order-SC duality. Our proposed mechanism for SC is the same for CTS in which the proximate semiconducting state is antiferromagnetic instead of charge-ordered, with the only difference that SC in the former is generated via a fluctuating spin-singlet state as opposed to static PEC. In Appendix B we point out that several classes of unconventional superconductors share the same band-fil...

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High-Pressure Study up to 9.9 GPa of Organic Mott Insulator, β'-(BEDT-TTF)₂AuCl₂

Cited by 11 publications

References 14 publications

Recent progress in high-pressure studies on organic conductors

Recent progress in high-pressure studies on organic conductors

Metallization of the Organic Conductor (TTM-TTP)I₃with a Highly One-Dimensional Half-Filled Band under Pressure beyond 7 GPa

From charge- and spin-ordering to superconductivity in the organic charge-transfer solids

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High-Pressure Study up to 9.9 GPa of Organic Mott Insulator, β'-(BEDT-TTF)2AuCl2

Cited by 11 publications

References 14 publications

Recent progress in high-pressure studies on organic conductors

Recent progress in high-pressure studies on organic conductors

Metallization of the Organic Conductor (TTM-TTP)I3with a Highly One-Dimensional Half-Filled Band under Pressure beyond 7 GPa

From charge- and spin-ordering to superconductivity in the organic charge-transfer solids

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Product

Resources

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High-Pressure Study up to 9.9 GPa of Organic Mott Insulator, β'-(BEDT-TTF)₂AuCl₂

Metallization of the Organic Conductor (TTM-TTP)I₃with a Highly One-Dimensional Half-Filled Band under Pressure beyond 7 GPa