Thermal diffusivity of superconducting YBa2Cu3O7−<i>x</i>

Abstract

Thermal diffusivity results for superconducting YBa2Cu3O7−x systems are reported. Two laser excitation techniques were used: photoacoustic phase-lag and the flash method. We observed an anomalous jump in the thermal diffusivity at the critical temperature and related it to the electronic specific heat anomaly. This correlation yielded a characteristic phonon frequency of 320 cm−1 in the range of an active Raman mode already observed in a single crystal of the same compound. This result reinforces the current electron-phonon coupling mechanism as responsible for superconductivity.