Charge ordering in α-(BEDT-TTF)2I3

Takano, Yoshiki; Hiraki, K.; Yamamoto, Hiroshi; Nakamura, Toshikazu; Takahashi, Tohru

doi:10.1016/s0379-6779(00)00683-4

Cited by 48 publications

(41 citation statements)

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“…Among the various known organic conductors [115][116][117][118], α-(BEDT-TTF) 2 I 3 (abbreviated as α-I 3 ) shows rich electronic properties such as charge ordering [119], superconductivity [120], zero-gap state (ZGS) [121,122], photo-induced phase transition [123], and nonlinear optical response [124].The crystal structure of α-I 3 consists of alternating layers of the anion and donor [125]. The donor layer has a herringbone arrangement of BEDT-TTF molecules.…”

Section: α-(Bedt-ttf) 2 I 3 and Related Compoundsmentioning

confidence: 99%

“…Before the theoretical prediction, Moldenhauer et al, reported that the localization of electrons occurs at the B and C sites whereas the electrons at the A and A′ sites are delocalized below T MI [12]. The 13 C-NMR study suggested the existence of two differently charged molecules below T MI [119,127]. Seo introduced intersite Coulomb interaction V, and he proposed that the localized charge would form a horizontal stripe [16].…”

Section: α-(Bedt-ttf) 2 I 3 and Related Compoundsmentioning

confidence: 99%

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Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Yakushi

2012

Crystals

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This paper reviews charge ordering in the organic conductors, β″-(BEDT-TTF) (TCNQ), θ-(BEDT-TTF) 2 X, and α-(BEDT-TTF) 2 X. Here, BEDT-TTF and TCNQ represent bis(ethylenedithio)tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane, respectively. These compounds, all of which have a quarter-filled band, were evaluated using infrared and Raman spectroscopy in addition to optical conductivity measurements. It was found that β″-(BEDT-TTF)(TCNQ) changes continuously from a uniform metal to a chargeordered metal with increasing temperature. Although charge disproportionation was clearly observed, long-range charge order is not realized. Among six θ-type salts, four compounds with a narrow band show the metal-insulator transition. However, they maintain a large amplitude of charge order (Δρ~0.6) in both metallic and insulating phases. In the X = CsZn(SCN) 4 salt with intermediate bandwidth, the amplitude of charge order is very small (Δρ < 0.07) over the whole temperature range. However, fluctuation of charge order is indicated in the Raman spectrum and optical conductivity. No indication of the fluctuation of charge order is found in the wide band X = I 3 salt. In α-(BEDT-TTF) 2 I 3 the amplitude of charge order changes discontinuously from small amplitude at high temperature to large amplitude (Δρ max~0 .6) at low temperature. The long-range chargeordered state shows ferroelectric polarization with fast optical response. The fluctuation of multiple stripes occurs in the high-temperature metallic phase. Among α-(BEDT-TTF) 2 MHg(SCN) 4 (X = NH 4 , K, Rb, Tl), the fluctuation of charge order is indicated only in the X = NH 4 salt. α′-(BEDT-TTF) 2 IBr 2 shows successive phase transitions to the ferroelectric state keeping a large amplitude of charge order (Δρ max~0 .8) over the whole temperature range. It was found that the amplitude and fluctuation of charge order in these compounds is enhanced as the kinetic energy (bandwidth) decreases. OPEN ACCESSCrystals 2012, 2 1292

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Section: α-(Bedt-ttf) 2 I 3 and Related Compoundsmentioning

confidence: 99%

Section: α-(Bedt-ttf) 2 I 3 and Related Compoundsmentioning

confidence: 99%

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Yakushi

2012

Crystals

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“…The low-energy excitations around the gapless points are described by massless Dirac fermions (DFs) with anisotropic linear energy-momentum dispersion [7]. At ambient P, the Dirac cones are likely present at high T, since recent 13 C-NMR studies found, in the local spin density i, a large difference among nonequivalent sites i (= A, A', B, and C) -B < A (= A') < C -with strong T dependence. It has been revealed that this feature is characteristic for the high-energy part of the DF-type excitations in a tilted Dirac-cone system like -I3 [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…

ABSTRACTThe spin excitations from the nonmagnetic charge-ordered insulating state of -(BEDT-TTF)2I3 at ambient pressure have been investigated by probing the static and lowfrequency dynamic spin susceptibilities via site-selective nuclear magnetic resonance at 13

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confidence: 99%

Spin excitations in the quasi-two-dimensional charge-ordered insulatorα−(BEDT−TTF)2I3probed via
Ishikawa
¹
,
Hirata
²
,
Liu
³

et al. 2016
Phys. Rev. B

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“…The features of these three kinds of molecules (A, B, and C) are different with each other. There exists the charge disproportionation even at high temperatures [31,32], and the relation is found as n C > n A = n A ′ > n B [33], where n α denotes the amount of the charge. The difference in the magnitude of n α becomes large under pressures [34].…”

Section: Introductionmentioning

confidence: 99%

Electronic properties close to Dirac cone in two-dimensional organic conductor α-(BEDT-TTF)2I3

2009

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Abstract. A zero-gap state (ZGS) has been found in a bulk system of two-dimensional organic conductor, α-(BEDT-TTF)2I3 salt which consists of four sites of donor molecules in a unit cell. In the present paper, the characteristic of the ZGS is analyzed in detail and the electronic properties are examined in the vicinity of the Dirac point where the conduction and valence bands degenerate to form the zero-gap. The eigenvectors of the energy band have four components of respective sites, where two of them correspond to inequivalent sites and the other two correspond to equivalent sites. It is shown that the former exhibits an exotic momentum dependence around the contact point and the latter shows almost a constant dependence. The density of states of each site close to the Dirac point is calculated to demonstrate the temperature dependence of the local magnetic susceptibility and the local nuclear magnetic relaxation rate. Further, the robust property of the ZGS against the anion potential is also shown by using the second-order perturbation.PACS. 71.10.-w Theories and models of many-electron systems -72.80.Le Polymers; organic compounds (including organic semiconductors)

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Charge ordering in α-(BEDT-TTF)2I3

Cited by 48 publications

References 0 publications

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Spin excitations in the quasi-two-dimensional charge-ordered insulatorα−(BEDT−TTF)2I3probed via
Ishikawa
¹
,
Hirata
²
,
Liu
³

et al. 2016
Phys. Rev. B

Electronic properties close to Dirac cone in two-dimensional organic conductor α-(BEDT-TTF)2I3

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Charge ordering in α-(BEDT-TTF)2I3

Cited by 48 publications

References 0 publications

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Spin excitations in the quasi-two-dimensional charge-ordered insulatorα−(BEDT−TTF)2I3probed viaIshikawa1, Hirata2, Liu3 et al. 2016Phys. Rev. B

Electronic properties close to Dirac cone in two-dimensional organic conductor α-(BEDT-TTF)2I3

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Product

Resources

About

Spin excitations in the quasi-two-dimensional charge-ordered insulatorα−(BEDT−TTF)2I3probed via
Ishikawa
¹
,
Hirata
²
,
Liu
³

et al. 2016
Phys. Rev. B