Reactance anisotropy in superconducting YBa2Cu3O7-x films

The reactance of thin epitaxial films of YBa₂Cu₃O_7-x has been measured as a function of temperature, frequency and film crystallographic orientation. The films were grown on SrTiO₅ and MgO single crystal substrates by in situ RF sputter deposition. For YBa₂Cu₃O_7-x deposited on SrTiO₃ [110] the film reactance is capacitive for temperatures between 300 K and T_c and frequencies above a few kilohertz. Below T_c the reactance of the films is inductive. For T>T_c the (resonant) frequency at which X=0 decreases for increasing temperatures and the films are inductive for frequencies less than the resonant frequency. For well orientated films deposited onto SrTiO₃ [100] and MgO [100] substrates the reactance is purely inductive for temperatures between 10-300 K and frequencies up to 13 MHz.