Anisotropic Properties of Superconducting (La1-xSrx)₂ CuO₄ Single-Crystal Thin Films

Anisotropies of resistivity and the upper critical magnetic field in superconducting (La 1- x SF x ) 2 CuO 4 single-crystal thin films are observed to be 20-30 and 5.3, respectively. It is found that the temperature dependence of resistivity along the c -axis is strongly affected by defects, while that along the Cu-O plane is much less affected. This causes the variation in the anisotropy factor of resistivity. The coherence length in the c -axis direction is estimated to be 0.71 nm. The results indicate that this material is very close to a two-dimensional superconductor or a superconductor in the crossover region.