Electron Paramagnetic Resonance in MexC60 Fullerites for Me = K and Rb

Abstract
EPR studies of superconducting fullerites MexC60 (Me = K and Rb) are performed for temperatures ranging from 4 to 300 K and compositions of x = 2 to 5. A paramagnetic center is an ion radical fullerene Ċ60 which may occur as a cation Ċ60+ or anion Ċ60y of different valency. The EPR signal of Ċ60+ weakly depends on temperature whereas the signal of Ċ60y in a Mex60)y complex is strongly dependent both on temperature and composition. A model of a paramagnetic center related to a wandering electron (hole) localized on the Ċ60 fullerene ball is presented.