Intradimer Charge Disproportionation in Triclinic-EtMe3P[Pd(dmit)2]2 (dmit: 1,3-Dithiole-2-thione-4,5-dithiolate)

Yamamoto, Takashi; Nakazawa, Yasuhiro; Tamura, Masafumi; Nakao, Akiko; Ikemoto, Yuka; Moriwaki, Toshimichi; Fukaya, A.; Kato, Reìzo; Yakushi, Kyuya

doi:10.1143/jpsj.80.123709

Cited by 17 publications

(24 citation statements)

References 11 publications

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“…The β'-type crystals (black elongated or hexagonal plates) were obtained as a single phase, with the exception of the EtMe 3 P salt. The EtMe 3 P salt contains a monoclinic P2 1 /m phase [17][18][19][20][21] as the main phase, and triclinic- [22] and β'-phases (monoclinic C2/c) as minor phases . The β'-phase of the EtMe 3 P salt was a very minor component.…”

Section: Methodsmentioning

confidence: 99%

Cation Dependence of Crystal Structure and Band Parameters in a Series of Molecular Conductors, β'-(Cation)[Pd(dmit)2]2 (dmit = 1,3-dithiole-2-thione-4,5-dithiolate)

Kato

Cui

2012

Crystals

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An isostructural series of anion radical salts, β'-(Et x Me 4−x Z) [Pd(dmit) 2 ] 2 (x = 0-2, Z = P, As, Sb), with a quasi-triangular lattice comprising the dimer unit [Pd(dmit) 2 ] 2 − belong to a strongly correlated electron system with geometrical frustration. Intra and interdimer transfer integrals between the frontier molecular orbitals, which characterize the strength of electron correlation and degree of frustration, can be tuned by selection of the counter cation. We have systematically analyzed the crystal structure with X-ray diffraction method and intermolecular transfer integrals using extended Hückel molecular orbital calculations based on structural data. The variation in the cation affects the unit cell in a manner equivalent to an anisotropic pressure. Increasing the covalent radius of the central atom Z and the number of ethyl groups (x) in the cation leads to slight arching of the Pd(dmit) 2 molecule. This arch-shaped distortion of the Pd(dmit) 2 molecule modifies the interdimer transfer integrals in formation of the regular triangular dimer lattice. On the other hand, the intradimer transfer integral, which is correlated with the effective on-site Coulomb interaction of the dimer, is weakly dependent on the type of cation.

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Section: Methodsmentioning

confidence: 99%

Cation Dependence of Crystal Structure and Band Parameters in a Series of Molecular Conductors, β'-(Cation)[Pd(dmit)2]2 (dmit = 1,3-dithiole-2-thione-4,5-dithiolate)

Kato

Cui

2012

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“…Under the pressurized condition, both complexes exhibit superconductivity, which was attributed to a pairedelectron liquid. The PEC model can be applied for not only β-(meso-DMBEDT-TTF) 2 X (X = PF 6 and AsF 6 ), but also thiospinel CuIr 2 S 4 [23] with the charge-ordered and the spin-dimerized transition at 230 K, and triclinic EtMe 3 P[Pd(dmit) 2 ] 2 [24] with the charge-ordered and the spin-gap transition.…”

Section: Magnetic Susceptibility Of β-(Meso-dmbedt-ttf) 2 X (X = Pf 6mentioning

confidence: 99%

Magnetism and Pressure-Induced Superconductivity of Checkerboard-Type Charge-Ordered Molecular Conductor β-(meso-DMBEDT-TTF)2X (X = PF6 and AsF6)

et al. 2012

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Abstract:The metallic state of the molecular conductor β-(meso-DMBEDT-TTF) 2 X (DMBEDT-TTF = 2- (5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiin-2-ylidene) -5,6-dihydro-5,6-dimethyl-1,3-dithiolo[4,5-b][1,4]dithiin, X = PF 6 , AsF 6 ) is transformed into the checkerboard-type charge-ordered state at around 75-80 K with accompanying metalinsulator (MI) transition on the anisotropic triangular lattice. With lowering temperatures, the magnetic susceptibility decreases gradually and reveals a sudden drop at the MI OPEN ACCESSCrystals 2012, 2 1503 transition. By applying pressure, the charge-ordered state is suppressed and superconductivity appears in β-(meso-DMBEDT-TTF) 2 AsF 6 as well as in the reported β-(meso-DMBEDT-TTF) 2 PF 6 . The charge-ordered spin-gapped state and the pressure-induced superconducting state are discussed through the paired-electron crystal (PEC) model, where the spin-bonded electron pairs stay and become mobile in the crystal, namely the valence-bond solid (VBS) and the resonant valence bonded (RVB) state in the quarter-filled band structure.

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“…As for [Pd(dmit) 2 ] 2 salts, the direction of the largest V is identical to that of the largest t. Nevertheless, the competition between V and bond alternation in the charge distribution is avoidable because of HOMO-LUMO inversion [20]. HOMO-LUMO inversion is induced by the fact that two [Pd(dmit) 2 ] molecules form a very tight dimer [21,22].…”

Section: Introductionmentioning

confidence: 99%

“…HOMO-LUMO inversion is induced by the fact that two [Pd(dmit) 2 ] molecules form a very tight dimer [21,22]. Owing to the inversion of the energy levels of molecular orbitals, the charge distribution required from V can cooperate with the bond order required from t [20][21][22][23]. This mechanism is significantly different from the TTF-based molecular conductors and quinone-based molecular conductors.…”

Section: Introductionmentioning

confidence: 99%

“…This mechanism is significantly different from the TTF-based molecular conductors and quinone-based molecular conductors. To the author's best knowledge, however, there are only three kinds of [Pd(dmit) 2 ] 2 salts which exhibit the charge ordered (CO) transition [20][21][22][23][24]. On the other hand, a number of the β"-type ET salts exhibit CO transition.…”

Section: Introductionmentioning

confidence: 99%

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Vibrational Spectra of β″-Type BEDT-TTF Salts: Relationship between Conducting Property, Time-Averaged Site Charge and Inter-Molecular Distance

Yamamoto

2012

Crystals

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Abstract:The relationship between the conducting behavior and the degree of charge fluctuation in the β″-type BEDT-TTF salts is reviewed from the standpoints of vibrational spectroscopy and crystal structure. A group of β″-type ET salts demonstrates the best model compounds for achieving the above relationship because the two-dimensional structure is simple and great diversity in conducting behavior is realized under ambient pressure. After describing the requirement for the model compound, the methodology for analyzing the results of the vibrational spectra is presented. Vibrational spectroscopy provides the time-averaged molecular charge, the charge distribution in the twodimensional layer, and the inter-molecular interactions, etc. The experimental results applied to 2/3-filled and 3/4-filled β″-type ET salts are reported. These experimental results suggest that the conducting property, the difference in the time-averaged molecular charges between the ionic and neutral-like sites, the alternation in the inter-molecular distances and the energy levels in the charge distributions are relevant to one another. The difference in the time-averaged molecular charges, ∆ρ, is a useful criterion for indicating conducting behavior. All superconductors presented in this review are characterized as small but finite ∆ρ.

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Intradimer Charge Disproportionation in Triclinic-EtMe₃P[Pd(dmit)₂]₂ (dmit: 1,3-Dithiole-2-thione-4,5-dithiolate)

Cited by 17 publications

References 11 publications

Cation Dependence of Crystal Structure and Band Parameters in a Series of Molecular Conductors, β'-(Cation)[Pd(dmit)2]2 (dmit = 1,3-dithiole-2-thione-4,5-dithiolate)

Cation Dependence of Crystal Structure and Band Parameters in a Series of Molecular Conductors, β'-(Cation)[Pd(dmit)2]2 (dmit = 1,3-dithiole-2-thione-4,5-dithiolate)

Magnetism and Pressure-Induced Superconductivity of Checkerboard-Type Charge-Ordered Molecular Conductor β-(meso-DMBEDT-TTF)2X (X = PF6 and AsF6)

Vibrational Spectra of β″-Type BEDT-TTF Salts: Relationship between Conducting Property, Time-Averaged Site Charge and Inter-Molecular Distance

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