Electron spin resonance in Rb xC 60 compounds observed at transition from superconducting to normal state

Abstract

The thermal treatment of Rb xC 60 samples allowed us to modify their crystalline structure to the state that only the ESR signals due to an on-molecule electronic state were observed. The ESR lines observed at low temperatures disappeared at temperatures corresponding to the transition from a normal to a superconducting state in therange of fluctuation of superconductivity, and appeared again above critical temperatures. The results allowed us to draw a tentative conclusion that the on-molecule electronic states are responsible for superconductivity in intercalated fullerides.