TWO UNUSUAL DETERMINATIONS OF ELECTRONIC AND LATTICE THERMAL PARAMETERS IN YBa2Cu3O7 Films

Abstract

This paper deals with the nanosecond transient electrical resistance following either an optical pulse or the sudden application of a critical current in YBCO films. The observed bi-exponential decay of the photoresistance yields both the electron-phonon relaxation time τep and the phonon escape time τγ to the substrate. A novel treatment of these data allows to derive the low-temperature electron specific heat and the electron-phonon coupling constant lambda in the acoustic regime. Secondly, the nucleation time of phase-slip centers in narrow bridges is analyzed to provide τγ. Finally, the accurate knowledge of τγ is used to determine the temperature inside a dissipation center.