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BEDT-TTF organic superconductors: the entangled role of phonons

Alberto Girlando·Matteo Masino·Aldo Brillante·Raffaele G. Della Valle·Elisabetta Venuti
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Abstract

We calculate the lattice phonons and the electron-phonon coupling of the organic superconductor κ-(BEDT-TTF)_2 I_3, reproducing all available experimental data connected to phonon dynamics. Low-frequency intra-molecular vibrations are strongly mixed to lattice phonons. Both acoustic and optical phonons are appreciably coupled to electrons through the modulation of the hopping integrals (e-LP coupling). By comparing the results relevant to superconducting κ- and β-(BEDT-TTF)_2 I_3, we show that electron-phonon coupling is fundamental to the pairing mechanism. Both e-LP and electron-molecular vibration (e-MV) coupling are essential to reproduce the critical temperatures. The e-LP coupling is stronger, but e-MV is instrumental to increase the average phonon frequency.

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Alberto Girlando, Matteo Masino, Aldo Brillante, Raffaele G. Della Valle, Elisabetta Venuti. 2002-10-16. BEDT-TTF organic superconductors: the entangled role of phonons. https://doi.org/10.1103/physrevb.66.100507

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