UPPER CRITICAL FIELD OF Mo-Ni HETEROSTRUCTURES

Upper critical field and its anisotropy have been measured on two very short wavelength Mo-Ni heterostructures of different degrees of perfection, λ = 13.8Å (disordered structure) and X = 16.6Å (layered structure). In both cases the parallel critical field has an unexpected temperature dependence, a large and temperature dependent anisotropy, and over 60% enhancement over the Clogston-Chandrasekhar limit. Data are fit to the Werthamer-Helfand-Hohenberg theory and the spin-orbit scattering times are found to be 1.79 × 10−13 sec and 2 × 10−13 sec, respectively.