SEM and electrical studies of current induced superconducting-resistive transitions in Y1Ba2Cu3O7−x thin films

Abstract

We studied the electrical current induced superconducting-resistive transitions in laser deposited c-axis oriented crystalline Y1Ba2Cu3O7−x superconducting thin films. Comparative studies of I-V characteristics of thin film bridges with different geometries at temperatures below Tc and SEM voltage imaging of current induced resistive regions in the same samples were performed. The I-V curves of these bridges had two nonlinear regimes, a gradual and an abrupt transition to the normal state. We concluded that the gradual nonlinear transition is caused by imperfections in the sample such as film and substrate defects, film thickness variation, etc., and by dissipative effects such as flux motion and superconductor/normal-metal/superconductor type behavior. The abrupt transition to the normal state in the I-V curve is ascribed to Joule heating. The SEM mapping provides a direct image of the above effects and is useful for material or device characterization and for studying the transport properties of high Tc films.