Catastrophic Local Degradation of YBa2Cu3Oy Epitaxial Film Induced by High Electric Field Application

This letter describes the first observation of catastrophic local degradation of epitaxially grown YBa2Cu3O y film due to pulsed high electric field application in the normal conduction state. In the degraded samples, a damaged region like a crack appears which was not seen in the sound stage. Cathodoluminescence image observation, which reflects the distribution of defects inside MgO substrates, suggested that the local degradation of YBa2Cu3O y film occurred where defects in the substrate materials were aggregated.