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Evidence of the superconducting energy gap in the optical spectra of $α_t$-(BEDT-TTF)$_{2}$I$_{3}$

N. Drichko·P. Haas·B. Gorshunov·D. Schweitzer·M. Dressel
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Abstract

The far-infrared in-plane reflectivity of the organic superconductor $α_t$-(BEDT-TTF)$_{2}$I$_{3}$ is measured down to frequencies of 10 cm$^{-1}$; the optical conductivity is obtained by a Kramers-Kronig procedure. In the superconducting state an energy gap opens at 25 cm$^{-1}$ which corresponds to $2Δ/k_BT_c = 4.4$ in agreement with moderate coupling. Even well below $T_c=8$ K a considerable absorption remains for $\hbarω<2Δ$. We discuss different posibilities to explain this behaviour.

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N. Drichko, P. Haas, B. Gorshunov, D. Schweitzer, M. Dressel. 2002-04-19. Evidence of the superconducting energy gap in the optical spectra of $α_t$-(BEDT-TTF)$_{2}$I$_{3}$. https://doi.org/10.1209/epl%2Fi2002-00193-6

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