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Akutsu, Hiroki; Saito, Kazuya; Sorai, Michio

doi:10.1103/physrevb.61.4346

Cited by 81 publications

(90 citation statements)

References 28 publications

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“…In this system, several measurements indicate that a glasslike structural transition, which is associated with a ordering of BEDT-TTF or anion molecules, occurs and has a significant effect on their electronic states under equilibrium [6][7][8][9][10]. However, effects of the structural transition on PIPT phenomena remain unclear.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced phase separation with local structural ordering in organic molecular conductors

et al. 2017

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In this work, polarized pump-probe spectroscopy was carried out to investigate the effects of a structural ordering of molecules on photoinduced phase separation (PIPS) in the organic conductors κ-(BEDT-TTF) 2 X [X = Cu[N(CN) 2 ]Br (κ-Br) and Cu(NCS) 2 (κ-NCS)]. We found that the anisotropic response for the probe polarization appeared at around T g , where the glasslike structural transition occurs. The anisotropy can be a result of a transient destruction of the local ordering of molecules, indicating a connection between the glasslike transition and PIPS. Moreover, we found that the PIPS response gradually develops with decreasing temperature in κ-Br, whereas it steeply increases in κ-NCS. This qualitative difference suggests that the structural ordering caused by a PIPS is more crucial in κ-NCS than in κ-Br.

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Section: Introductionmentioning

confidence: 99%

Photoinduced phase separation with local structural ordering in organic molecular conductors

et al. 2017

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“…The presence of both metallic and insulating states at low temperatures is probably related to progressive freezing-in of disorder associated with the terminal ethylene-groups of BEDT-TTF ͑which can adopt either a ''staggered'' or ''eclipsed'' configuration͒ and/or with the anions, X. [11][12][13][14][15] As yet there is no strong theoretical concurrence on the mechanism for superconductivity in the BEDT-TTF salts, 3,16 with electron-electron interactions, spin fluctuations, 17 charge fluctuations, 18 and electron-phonon interactions 19 under consideration. It is therefore unclear as to whether the mixed insulating/metallic phase referred to above is a prerequisite for or a hindrance to superconductivity.…”

Section: Introductionmentioning

confidence: 99%

Fermi-surface topology and the effects of intrinsic disorder in a class of charge-transfer salts containing magnetic ions:β″−(BEDT−TTF)
Coldea
¹
,
Bangura
²
,
Singleton
³

et al. 2004
Phys. Rev. B
51
1
21
0
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We report high-field magnetotransport measurements on ␤Љ-(BEDT-TTF) 4 ͓(H 3 O)M (C 2 O 4 ) 3 ͔Y , where M ϭGa, Cr, and Fe and Y ϭC 5 H 5 N. We observe similar Shubnikov-de Haas oscillations in all compounds, attributable to four quasi-two-dimensional Fermi-surface pockets, the largest of which corresponds to a crosssectional area Ϸ8.5% of the Brillouin zone. The cross-sectional areas of the pockets are in agreement with the expectations for a compensated semimetal, and the corresponding effective masses are ϳm e , rather small compared to those of other BEDT-TTF salts. Apart from the case of the smallest Fermi-surface pocket, varying the M ion seems to have little effect on the overall Fermi-surface topology or on the effective masses. Despite the fact that all samples show quantum oscillations at low temperatures, indicative of Fermi liquid behavior, the sample and temperature dependence of the interlayer resistivity suggest that these systems are intrinsically inhomogeneous. It is thought that intrinsic tendency to disorder in the anions and/or the ethylene groups of the BEDT-TTF molecules leads to the coexistence of insulating and metallic states at low temperatures. A notional phase diagram is given for the general family of ␤Љ-(BEDT-TTF) 4 ͓(H 3 O)M (C 2 O 4 ) 3 ͔Y salts.

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“…The EEG ordering process, however, cannot be completed for kinetic reasons, since upon lowering the temperature their molecular motion/rotation slows down so rapidly that thermodynamic equilibrium cannot be reached and a short-range structural order becomes frozen-in. This is a glass-like transition [21][22][23][24] , and the degree of EEG order/disorder depends on the glass transition temperature T g , which in turn varies with the cooling rate q = dT /dt such that faster cooling results in a higher T g and a larger degree of frozen-in disorder on the population of the E and S states 25 , see 3 for an overview. The effect of the EEG glass-like ordering transition on the electronic (ground-state) properties is twofold: (i) The strong vibrations lead to an enhanced scattering contribution at elevated temperatures above T g 26, 27 and their frozen-in configuration below T g causes a random lattice potential, which gives rise to an additional contribution to the residual resistivity and affects the superconducting state and transition temperature 6,13,14,28 .…”

Section: Introductionmentioning

confidence: 99%

Mott metal-insulator transition induced by utilizing a glasslike structural ordering in low-dimensional molecular conductors

2014

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We utilize a glass-like structural transition in order to induce a Mott metal-insulator transition in the quasi-two-dimensional organic charge-transfer salt κ-(BEDT-TTF)2Cu[N(CN)2]Br. In this material, the terminal ethylene groups of the BEDT-TTF molecules can adopt two different structural orientations within the crystal structure, namely eclipsed (E) and staggered (S) with the relative orientation of the outer C-C bonds being parallel and canted, respectively. These two conformations are thermally disordered at room temperature and undergo a glass-like ordering transition at Tg ∼ 75 K. When cooling through Tg, a small fraction that depends on the cooling rate remains frozen in the S configuration, which is of slightly higher energy, corresponding to a controllable degree of structural disorder. We demonstrate that, when thermally coupled to a low-temperature heat bath, a pulsed heating current through the sample causes a very fast relaxation with cooling rates at Tg of the order of several 1000 K/min. The freezing of the structural degrees of freedom causes a decrease of the electronic bandwidth W with increasing cooling rate, and hence a Mott metal-insulator transition as the system crosses the critical ratio (W/U )c of bandwidth to on-site Coulomb repulsion U . Due to the glassy character of the transition, the effect is persistent below Tg and can be reversibly repeated by melting the frozen configuration upon warming above Tg. Both by exploiting the characteristics of slowly-changing relaxation times close to this temperature and by controlling the heating power, the materials can be fine-tuned across the Mott transition. A simple model allows for an estimate of the energy difference between the E and S state as well as the accompanying degree of frozen disorder in the population of the two orientations.

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Phase behavior of the organic superconductorsκ−(BEDT−TTF

Cited by 81 publications

References 28 publications

Photoinduced phase separation with local structural ordering in organic molecular conductors

Photoinduced phase separation with local structural ordering in organic molecular conductors

Fermi-surface topology and the effects of intrinsic disorder in a class of charge-transfer salts containing magnetic ions:β″−(BEDT−TTF)
Coldea
¹
,
Bangura
²
,
Singleton
³

et al. 2004
Phys. Rev. B
51
1
21
0
View full text Add to dashboard Cite

Mott metal-insulator transition induced by utilizing a glasslike structural ordering in low-dimensional molecular conductors

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Phase behavior of the organic superconductorsκ−(BEDT−TTF

Cited by 81 publications

References 28 publications

Photoinduced phase separation with local structural ordering in organic molecular conductors

Photoinduced phase separation with local structural ordering in organic molecular conductors

Fermi-surface topology and the effects of intrinsic disorder in a class of charge-transfer salts containing magnetic ions:β″−(BEDT−TTF)Coldea1, Bangura2, Singleton3 et al. 2004Phys. Rev. B511210View full textAdd to dashboardCite

Mott metal-insulator transition induced by utilizing a glasslike structural ordering in low-dimensional molecular conductors

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Product

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About

Fermi-surface topology and the effects of intrinsic disorder in a class of charge-transfer salts containing magnetic ions:β″−(BEDT−TTF)
Coldea
¹
,
Bangura
²
,
Singleton
³

et al. 2004
Phys. Rev. B
51
1
21
0
View full text Add to dashboard Cite