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Small-q phonon-mediated superconductivity in organic κ-BEDT-TTF compounds

G. Varelogiannis
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Abstract

We propose a mew picture for superconductivity in $κ-(BEDT-TTF)_2X$ salts arguing that small-{\bf q} electron-phonon scattering dominates the pairing. We reproduce the distinct X-shaped d-wave gap reported recently by magnetooptic measurements and we argue that the softness of the momentum structure of the gap and the near degeneracy of s- and d-wave gap states may be at the origin of the experimental controversy about the gap symmetry. We show that a magnetic field applied parallel to the planes may induce extended gapless-regions on the FS accounting for the experimental signatures of a Fulde-Ferrel-Larkin-Ovchinikov state and it may induce gap symmetry transitions as well.

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G. Varelogiannis. 2001-07-01. Small-q phonon-mediated superconductivity in organic κ-BEDT-TTF compounds. https://doi.org/10.1103/physrevlett.88.117005

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