COMPLETE OPTICAL-RESPONSE OF THE MAGNETIC FULLERENE DERIVATIVE TETRAKIS(DIMETHYLAMINO)ETHYLENE-C-60

We have measured the electrodynamic response of TDAE-C60 [where TDAE is tetrakis(dimethylamino) ethylene], which undergoes a ferromagnetic phase transition at Tc=16 K. The optical conductivity does not display a clear metallic component, which indicates that TDAE-C60 is not an itinerant ferromagnet. Moreover, the optical response is temperature independent and thus unaffected by the ferromagnetic phase transition at Tc. We also found several absorption peaks in the far-infrared spectral range, which are associated with the molecular phonon-mode spectrum of C60 and TDAE. © 1995 The American Physical Society.