Electrical transport properties of thin cadmium films at low temperatures

Abstract

We report here the results of an extensive study of localization and electron-electron interaction effects in thin cadmium films with thickness ranging from 80 A to 350 A. Measurements of the resistance as a function of both temperature and magnetic field have allowed us to separate the contributions of localization and electron-electron interaction. The low resistive films of thicknesses 300 A and 350 A do not show any localization. The resistance of these samples decreases logarithmically with decreasing temperature below 10 K, while a ln(T) increases in resistance is observed for the high resistive films of thickness in the range of 80–120 A. Magnetoresistance of low resistive samples obeys the expression ΔR(H)/R(O)=ATn. But, both the resistance and magnetoconductance of the high resistive films are well explained by weak localization and electron-electron interaction effect. From the magnetoconductance measurement, we have calculated the inelastic scattering time (τi) and the spin-orbit scattering time (τso). The magnitude of spin-orbit scattering time is smaller than the inelastic scattering time. The inelastic scattering has been shown to arise due to the electron-electron scattering and the absolute magnitude of this scattering rate agrees reasonably well with the theory within the temperature range 1.8 K≤T≤5 K. At higher temperature (5 K<T≤20 K), the inelastic scattering time obeys the expression τi∝T−2, due to electronphonon scattering.