Exchange narrowing of dipolar broadened epr lines in superconductors

Abstract

The exchange narrowing of dipolar broadened paramagnetic resonance (EPR) lines by the long range exchange interaction is considered. That is the actual situation. in magnetically diluted superconducting alloys, where a sharp decrease of the EPR linewidth under the superconducting transition was observed. These calculations show that the EPR linewidth drop below the superconducting transition temperature is a clear indication of the long wave-length electronic susceptibility decreasing in the superconducting state. © 1987 IEEE