APPLICATION OF ESR TO HIGH-T_c SUPERCONDUCTORS AND RELATED MATERIALS IV: ALKALI K DOPING EFFECTS ON THE SUPERCONDUCTING CHARACTERISTICS OF K₃C₆₀

Abstract

Several samples of K 3 C 60 have been made by the calcination of C 60 powder plus K flakes in evacuated quartz tubes at temperatures between 100°C and 700°C for 24 hours. The non-resonant microwave absorption (NRMA) measurements have been done below T c for these samples. From the linewidths and intensities of the NRMA signals, the superconducting properties (T c superconducting volume fraction and vortex size) have been studied as a function of the calcination temperature.

Electron Spin Resonance: A Major Probe for Molecular Conductors

“…Low field microwave absorption was also used to characterize superconductivity in C 60 salts, essentially on powder samples. − The kinetics of formation of a superconducting phase, ,,− the air stability of K 3 C 60 or the isotopic effect in M x C 60 salts was also studied by this technique. Because of its sensibility, thin films or Langmuir Blodgett multilayers were also characterized. , Figure shows a typical result found for A 3 C 60 salts 486a.…”