Weak localization and interaction effects in amorphous Ta/Ge multilayers

Abstract

We have measured the in-plane resistivity of amorphous Ta/Ge multilayers with individual layer thicknesses of between 0.4 and 34 nm from 1.5 to 300 K. Conduction occurs principally through the Ta layers, allowing us to study the effects of reduced dimensions in a structurally disordered metal. At high temperatures the negative temperature coefficient of resistance can be described in terms of the destruction of quantum interference by phonons. At lower temperatures a turnover to a positive temperature coefficient of resistance is seen, suggesting that spin-orbit scattering becomes important. At still lower temperatures the resistance is dominated by electron-electron interaction effects and we have observed a transition from two-dimensional to three-dimensional behaviour as the Ta layer thickness is increased.