POINT-CONTACT SPECTROSCOPY OF THE ELECTRON-PHONON INTERACTION IN THE LAYERED CONDUCTOR BETA-(BIS(ETHYLENEDITHIO)TETRATHIOFULVALENE)2I3

A theory of point contact (PC) spectroscopy of the electron-phonon interaction in layered conductors with a quasi-two-dimensional energy spectrum of charge carriers is developed. The predicted anisotropy of the PC spectra is observed on heterocontacts of Cu and the organic metal beta-(BEDT-TTF)2I3. Two types of PC spectrum are revealed, which correspond to different orientations of the contact axis. The spectrum measured on contacts with the current flow in the plane of the organic molecule layer display features caused by the interaction between the electrons and intramolecular vibrations. The spectra of the samples with the axis perpendicular to the BEDT-TIF layers have maxima reflecting the predominating contribution of the I3- anions in the processes of energy relaxation of the current carriers in such PCS.