Localization and electron-electron interaction effects in thin Bi wires and films

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Abstract
We report the results of a comprehensive study of localization and electron-electron interaction effects in thin Bi wires and films. Measurements of the resistance as a function of both temperature and magnetic field over a wide range have allowed us to separate the contributions of localization and interactions to the resistance, and to determine the electron inelastic-scattering time. The overall behavior is in general accord with the theory. The contribution of interactions is characterized by a screening parameter, F, whose value is consistent with theoretical expectations. The inelastic scattering appears to be due to electron-electron scattering, and the absolute magnitude of the scattering rate agrees reasonably well with the theory. However, several aspects of our results are not understood. First, relatively thick (≳600 Å) films exhibit an anomalously large resistance change as a function of temperature, which cannot be simply ascribed to a transition to three-dimensional behavior. Second, contrary to theoretical predictions, the dimensionality of the electron-electron scattering does not appear to always be the same as that of the electron-electron interaction effects. There is a range of wire diameter and of film thickness in which the scattering is three dimensional, while the interaction effects are one or two dimensional, respectively. This suggests that the important length scales for these processes are still not completely understood.