Measurement of the Superconducting Order-Parameter Relaxation Time from Harmonic Generation

The measured third harmonic power output from a paramagnetically doped superconductor in a stron microwave field has been found to vary with temperature as ${\mathrm{}(1-t)\mathrm{}}^{-1\mathrm{}}$, as predicted by Gor'kov and Eliashberg's theory for concentrations close to critical and Eliashberg's theory for the dilute alloy. The magnitude of the order-parameter relaxation time deduced from the measured power is consistent with a model constructed from these two theories.