Resonance Raman investigations of the electron phonon coupling in the organic superconductors β-(BEDT-TTF)2IAuI and κ-(BEDT-TTF)2I3

We investigated the resonance Raman scattering of the low energetic modes of the organic superconductors β-(BEDT-TTF)2IAuI (Tc= 4 K) and κ-(BEDT-TTF)2I3 (Tc = 4 K). In the κ-phase of (BEDT-TTF)2I3 6 low energetic phonons below 100 cm−1 exist. No distinct change in the phonon structure occurs on going from the normal to the superconducting state. In the β-phase of (BEDT-TTF)2IAuI only two phonon modes at 27 cm−1 and 33 cm−1 are observed. On cooling from the normal to the superconducting state the intensity of these modes drops by a factor of about 5. Similar effects were already observed in other β-phases of organic superconductors.