Synthetic analyses of T-c and H-c2 of NbTi/Nb superconductor/superconductor superlattice

Based on an improved calculation formalism of the proximity effect, the tra nsition temperature T-c, the parallel (H-c2 parallel to) and perpendicular (H-c2 perpendicular to) critical fields of the Nb50Ti50/Nb superlattice hav e been analyzed as a function of the structural modulation wavelength lambd a (s). T-c, H-c2 parallel to and H-c2 perpendicular to have been calculated using a unified set of the material parameters and allowing for the transi tion of the center of the order parameter between the NbTi and Nb layers. T he calculation has systematically reproduced the characteristics of H-c2 pa rallel to and H-c2 perpendicular to including the two-step dimensional cros sover of H-c2 parallel to(T) and the anomalous upward curvature of H-c2 per pendicular to(T).