Anisotropic critical fields in superconducting superlattices

Abstract

The temperature and angular dependence of critical fields (${H}_{c}$) have been studied as a function of layer thickness for superconducting Nb/Cu superlattices. For layer thicknesses between 100 and 300 \AA{}, dimensional crossover has been observed in the temperature dependence of ${H}_{c}$. Associated with the crossover we find a change in the angular dependence of ${H}_{c}$ to that given by the effective-mass theory. This is the first time that a relationship has been found between dimensional crossover observed in the temperature dependence and that in the angular dependence of critical fields.