Field dependence of harmonic responses and their anisotropy in YBa2Cu3O7+δ thin films

Abstract

The electrodynamic behaviour of the high-temperature superconductors is strongly affected by the anisotropy of these layered materials. When a pair of coils is positioned on opposite sides of a superconducting thin film, measurements of their mutual inductance can be used to infer the anisotropy of the superconductor. The fundamental and higher harmonic responses of YBa2Cu3O7+δ (YBCO) thin films to an alternating driving signal have been studied experimentally as a function of magnetic field for various angles between the applied field and the film plane at several temperatures. The measured data for different angles can be scaled onto a single curve using a three-dimensional scaling relation. The derived anisotropic parameter ranges from 4.4 to 4.8 in the measured temperature region, and is close to that from transport measurements.