skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Upper critical field of V-Ag multilayered superconductors

Journal Article · · Phys. Rev. B: Condens. Matter; (United States)

We report investigations of the upper critical field (H/sub c//sub 2//sub perpendicular/ and H/sub c//sub 2//sub X/) of V-Ag proximity-coupled superconducting multilayer structures, prepared by ultrahigh-vacuum electron-beam evaporation. By means of x-ray diffraction analysis, successful formation of an artificial superstructure is confirmed. From resistivity measurement parallel to the layers, the electron mean free paths in the V and Ag layers are determined. With reference to these transport properties, characterization of H/sub c//sub 2/ has been made. For three-dimensional multilayer structures, H/sub c//sub 2/ is analyzed in terms of the temperature dependence of H/sub c//sub 2//sub perpendicular/, the zero-temperature coherence length, and the anisotropy H/sub c//sub 2//sub X//H/sub c2//sub perpendicular/. Our results are in quantitative agreement with the relevant theories. For quasi-two-dimensional multilayer structures, a peculiar temperature dependence has been revealed in both H/sub c//sub 2//sub perpendicular/ and H/sub c//sub 2//sub X/. H/sub c//sub 2//sub perpendicular/ exhibits positive curvature near T/sub c/, and it is continuously enhanced with the increase of multilayer period, as predicted theoretically. In contrast with the monotonic variation in H/sub c//sub 2//sub perpendicular/, a drastic upturn at a certain temperature (dimensional crossover) and an upward inflection at a higher temperature have been observed in H/sub c//sub 2//sub X/. These two types of anomalies in H/sub c//sub 2//sub X/ are discussed in the context of the commensurability between the multilayer structure and the vortex lattice.

Research Organization:
Institute for Chemical Research, Kyoto University, Uji 611, Japan
OSTI ID:
5924636
Journal Information:
Phys. Rev. B: Condens. Matter; (United States), Vol. 35:13
Country of Publication:
United States
Language:
English