Two dimensional nature of the critical current anisotropy in epitaxial Nd 1.85Ce 0.15CuO 4−δ thin films

Abstract

We report our studies of the angular magnetic field dependence of the critical current density in epitaxial thin films of Nd 1.85Ce 0.15CuO 4−δ in the temperature range 1.4 K to 14 K. At low temperatures, the critical current anisotropy is well described by the 2D model of Josephson- coupled vortices. At temperatures above 10K, we observe deviations from the 2D behavior which may be attributed to the temperature dependence of the coherence length. The field dependence of the critical current density for the field orientation parallel to the CuO 2 planes is consistent with the dimensionality indicated by the angular dependence at all temperatures.