Raman scattering in ferromagnetic TDAE-C 60 compared to TDAE-C 70

Abstract

The Raman scattering at 1.16 eV laser excitation has been studied in ferromagnetic TDAE-C 60 and compared to that in paramagnetic TDAE-C 70. The shift of H g and A g modes in TDAE-C 60 indicates transfer of one electron to C 60 while the broadening of H g modes is quite similar to metallic K 3C 60 meaning significant electron-phonon coupling of this Jahn - Teller vibrations. In TDAE-C 70 the lines are narrow sugesting suppresed electron - phonon interaction and hence smaller polaronic effects. Below T c of magnetic ordering the two-magnon excitations are not seen clearly however the low energy part of spectra shows somewhat increased intensity. Upon air-exposure of TDAE-C 60 all H g and A g Raman modes disappear while a new band appears at 1848 cm −1.