Pressure-induced insulating state in an organic superconductor
Pressure-induced insulating state in an organic superconductor
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有机超导体中压力诱导的绝缘状态
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
G. L. Gard
中科院分区：
文献类型：
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作者：
J. Hagel;J. Wosnitza;C. Pfleiderer;J. Schlueter;J. Mohtasham;G. L. Gard
The electronic-transport properties of the quasi-two-dimensional organic superconductor ${ensuremath{eta}}^{ensuremath{'}}ensuremath{-}(mathrm{BEDT}ensuremath{-}mathrm{TTF}{)}_{2}{mathrm{SF}}_{5}{mathrm{CH}}_{2}{mathrm{CF}}_{2}{mathrm{SO}}_{3},$ where BEDT-TTF stands for bisethylenedithio-tetrathiafulvalene, have been investigated in magnetic fields up to 15 T and under hydrostatic pressure up to about 14 kbars. Shubnikov--de Haas data reveal a nonmonotonic pressure dependence of the holelike Fermi surface, a roughly linear increase of the electron g factor, and an approximately linear decrease of the cyclotron effective mass. By assuming that the latter reflects the pressure-induced reduction of the superconducting coupling parameter $ensuremath{lambda}$ the rapid reduction of the superconducting transition temperature ${T}_{c}(p)$ can be reasonably well described by the modified McMillan equation. Above about 12 kbars the material becomes insulating with an activated resistive behavior. This first-order metal-insulator transition has a hysteresis of about 3 kbars. This unexpected behavior is assumed to be of structural origin, although clear changes of electronic band-structure properties precede the phase transition.
The electronic-transport properties of the quasi-two-dimensional organic superconductor ${ensuremath{eta}}^{ensuremath{'}}ensuremath{-}(mathrm{BEDT}ensuremath{-}mathrm{TTF}{)}_{2}{mathrm{SF}}_{5}{mathrm{CH}}_{2}{mathrm{CF}}_{2}{mathrm{SO}}_{3},$ where BEDT-TTF stands for bisethylenedithio-tetrathiafulvalene, have been investigated in magnetic fields up to 15 T and under hydrostatic pressure up to about 14 kbars. Shubnikov--de Haas data reveal a nonmonotonic pressure dependence of the holelike Fermi surface, a roughly linear increase of the electron g factor, and an approximately linear decrease of the cyclotron effective mass. By assuming that the latter reflects the pressure-induced reduction of the superconducting coupling parameter $ensuremath{lambda}$ the rapid reduction of the superconducting transition temperature ${T}_{c}(p)$ can be reasonably well described by the modified McMillan equation. Above about 12 kbars the material becomes insulating with an activated resistive behavior. This first-order metal-insulator transition has a hysteresis of about 3 kbars. This unexpected behavior is assumed to be of structural origin, although clear changes of electronic band-structure properties precede the phase transition.