Electron localization effects on the low-temperature high-field magnetoresistivity of three-dimensional amorphous superconductors

Abstract

The electrical resistivity (Formula presented) of three-dimensional amorphous superconducting films (Formula presented)-(Formula presented) and (Formula presented)-(Formula presented) is measured in magnetic fields (Formula presented) up to 30 T. At low temperatures and at magnetic fields above the upper critical field (Formula presented), (Formula presented) is temperature independent and decreases as a function of magnetic field. This field dependence is consistent with localization theory in the high-field limit (Formula presented), where (Formula presented) is the phase-coherence length]. Above the superconducting transition temperature (Formula presented) the temperature dependence of the conductivity is consistent with inelastic scattering processes which are destructive to the phase coherence for electron localization, thereby allowing estimates for (Formula presented). The Hall effect data on (Formula presented)-(Formula presented), in conjunction with the resistivity data, allow the determination of the carrier concentration and mean free path. The upper critical field is comparable to (in (Formula presented)-(Formula presented) and significantly larger than (in (Formula presented)-(Formula presented) the Clogston-Chandrasekhar paramagnetic limit. This phenomenon is discussed in the context of electron localization. © 1998 The American Physical Society.