The Nb/NbZr multilayer is a typical one composed of two materials with the same bulk transition temperature and different electron diffusion constants and exhibits an anomalous upturn at T+ in the temperature dependence of parallel upper critical field Hc2∥(T). For all samples which show the upturn behavior in Hc2∥(T), we have found the anomalous minimum and maximum at a tilt of angle θ = θ* and a perpendicular direction θ = 0, respectively. Of particular interest is the existence of a different tendency in the variation of θ* and Hc2⊥-peak as a function of T below and above T+. From our experimental results, we suggest the dimensional crossover of the localization of Δ(r) for a tilt of angle. The angular dependence of Hc2(T) has been in a good agreement with the numerical calculations.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering