A New Dimer Mott Insulator: κ-(BEDT-TTF)<sub>2</sub>TaF<sub>6</sub>

Kawamoto, Tadashi; Kurata, Kohei; Mori, Takehiko

doi:10.7566/jpsj.87.083703

Cited by 9 publications

(6 citation statements)

References 40 publications

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“…Unfortunately, the small size of the crystals which could be obtained prevented the direct measurement of the conductivity in the single crystals. A pressed pellet was made from the material available, and the conductivity measured in the pellet was 1.7 × 10 –3 S cm –1 at 300 K. This value for the conductivity at room temperature is compatible with the expected Mott insulating behavior. − …”

Section: Resultssupporting

confidence: 58%

Bromide and Tribromide 4-Cyanobenzene-Ethylenedithio-Tetrathiafulvalene Radical Salts by Chemical and Electrochemical Routes

Varatojo

Lopes

Gama

et al. 2019

Crystal Growth & Design

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Two salts of the dissymmetric TTF-derivative 4-cyanobenzene-ethylenedithio-tetrathiafulvalene (4-CNB-EDT-TTF) with bromide and tribromide anions and with different stoichiometries, namely, (1:1) (4-CNB-EDT-TTF)-Br 3 (1) and (4:1) (4-CNB-EDT-TTF) 4 Br (2), were obtained by electrocrystallization and diffusion methods, respectively. The crystal structures of these compounds, as determined by single-crystal X-ray diffraction, are based on head-to-tail donor dimers with ring over ring overlap and donor stack arrangement, interleaved by anions depending on the (1:1) or (4:1) salt, respectively. The 4:1 salt behaves as a Mott insulator. In both salts, the donors are connected to adjacent donors through C−N•••H−C interactions, which can be described as an modified R 2 4 (10)* synthon for 1 and a combination of R 2 2 (10) and R 2 4 (10) synthons for 2.

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Section: Resultssupporting

confidence: 58%

Bromide and Tribromide 4-Cyanobenzene-Ethylenedithio-Tetrathiafulvalene Radical Salts by Chemical and Electrochemical Routes

Varatojo

Lopes

Gama

et al. 2019

Crystal Growth & Design

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“…(i) SL behavior has perhaps been seen in κ-(ET) 2 TaF 6 (hereafter κ-TaF 6 ) 54 , with |t ′ /t| > 1.5. Absence of magnetic ordering has been demonstrated down to 1.6 K 54 .…”

Section: New Quasi-1d Cts and Theoretical Challengesmentioning

confidence: 99%

Theory of triangular lattice quasi-one-dimensional charge-transfer solids

2019

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Recent investigations of the magnetic properties and the discovery of superconductivity in quasione-dimensional triangular lattice organic charge-transfer solids have indicated the severe limitations of the effective 1 2 -filled band Hubbard model for these and related systems. We present computational studies within the 1 4 -filled band Hubbard model for these highly anisotropic systems. Individual organic monomer molecules, and not their dimers, constitute the sites of the Hamiltonian within our theory. We find enhancement of the long-range component of superconducting pairing correlations by the Hubbard repulsive interaction U for band parameters corresponding to κ-(BEDT-TTF)2CF3SO3, which is superconducting under moderate pressure. We find significantly weaker superconducting pairing at realistic values of U in κ-(BEDT-TTF)2B(CN)4, and we ascribe the experimentally observed transition to a spin-gapped insulator to the formation of a paired-electron crystal. We make the testable prediction that the spin gap will be accompanied by charge-ordering and period doubling in two lattice directions. The weaker tendency to superconductivity in κ-(BEDT-TTF)2B(CN)4 compared to κ-(BEDT-TTF)2CF3SO3 is consistent with the more one-dimensional character of the former. Pressure-induced superconductivity is, however, conceivable. The overall results support a valence bond theory of superconductivity we have proposed recently.

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“…Ion radical salts with t ′/ t > 1 are a research topic of great current interest, − because their electronic ground state remains far from consensus from both experimental and theoretical perspectives. It is noteworthy that the t ′/ t value of 2 greatly exceeds those of the reported κ-(ET) 2 X salts with t ′/ t > 1; 1.09 for X = Cu 2 (CN) 3 – (quantum spin liquid), 1.16 for Ag 0.98 Cu 1.02 (CN) 3 – (quantum spin liquid), 1.42 for X = B(CN) 4 – (valence bond crystal), 1.76 for X = TaF 6 – (quantum spin liquid), and 1.79 for X = CF 3 SO 3 – (antiferromagnet). , …”

Section: Resultsmentioning

confidence: 72%

Bis(ethylenedithio)tetrathiafulvalene Cation Radical Salts Composed of Nonuniform Silver(I) Complex Polyanions

et al. 2019

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Rational control of the molecular arrangement in solids has been the subject of intense research for many years. In particular, the structural control of bis(ethylenedithio)tetrathiafulvalene (ET) radical cations has attracted special interest because of the primary effect on the electronic properties of the salts. In this study, we obtained the first ET cation radical salts formed with nonuniform silver(I) complex polyanions, which involve multiple kinds of openings in the anionic layer, by an electrocrystallization method. θ-(ET)2Ag2(CN)[N(CN)2]2 (1) with a θ-type ET packing motif contains double helical chains composed of AgN(CN)2, whereas α″-(ET)2Ag2(CN)(SCN)2 (2) with an α″-type ET packing motif contains zigzag ladders composed of AgSCN. Both silver(I)-based tube-like assemblies are connected to each other by a cyano group, affording nonuniform polyanionic structures. Although both salts show semiconducting behavior, there is a distinct difference in their spin geometry, with an S = 1/2 Heisenberg antiferromagnetic square lattice in 1, which is associated with charge disproportionation or dynamical charge fluctuation in the ET layers, and an S = 1/2 Heisenberg anisotropic triangular lattice in 2, which results in spin frustration in the ET layers. The ability of the nonuniform polymeric structures in the anionic layers to act as templates for various arrangements of ET radical cations is demonstrated.

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A New Dimer Mott Insulator: κ-(BEDT-TTF)₂TaF₆

Cited by 9 publications

References 40 publications

Bromide and Tribromide 4-Cyanobenzene-Ethylenedithio-Tetrathiafulvalene Radical Salts by Chemical and Electrochemical Routes

Bromide and Tribromide 4-Cyanobenzene-Ethylenedithio-Tetrathiafulvalene Radical Salts by Chemical and Electrochemical Routes

Theory of triangular lattice quasi-one-dimensional charge-transfer solids

Bis(ethylenedithio)tetrathiafulvalene Cation Radical Salts Composed of Nonuniform Silver(I) Complex Polyanions

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A New Dimer Mott Insulator: κ-(BEDT-TTF)2TaF6

Cited by 9 publications

References 40 publications

Bromide and Tribromide 4-Cyanobenzene-Ethylenedithio-Tetrathiafulvalene Radical Salts by Chemical and Electrochemical Routes

Bromide and Tribromide 4-Cyanobenzene-Ethylenedithio-Tetrathiafulvalene Radical Salts by Chemical and Electrochemical Routes

Theory of triangular lattice quasi-one-dimensional charge-transfer solids

Bis(ethylenedithio)tetrathiafulvalene Cation Radical Salts Composed of Nonuniform Silver(I) Complex Polyanions

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A New Dimer Mott Insulator: κ-(BEDT-TTF)₂TaF₆