Anisotropy of transport critical currents and two-dimensionality of vortex motion in YBa2Cu3O7-δ and Nd2-xCex thin films

Abstract The transport critical current density J c in thin films of YBa 2 Cu 3 O 7−δ (YBCO) and Nd 2− x Ce x CuO 4 (NCCO) is studied as a function of angles between the applied magnetic flux density B and the ab plane. Above the 2D-3D dimensional crossover temperature T cross , the dimensionality of the vortex motion is 3D due to the weak intrinsic pinning. With decrease of T , however, 2D vortex motion occurs not at T cross but at the characteristic temperature T ∗ ( T cross ). The vortex dynamics related to the dimensionality and to the intrinsic pinning are discussed on the basis of the two-dimensionality parameter ξ c ( T )/ s . Here ξ c is the coherence length along the c axis and s is the distance between the CuO 2 planes.