Weak Localization and Coulomb Interaction in Graphite Acceptor Intercalation Compounds
The transport properties of two-dimensional (2D) weakly disordered electronic systems have been the subject of great interest in the last few years. Theoretical and experimental investigations of the low-temperature electrical resistivity of a variety of 2D systems have led to the observation of new and anomalous non metallic effects. The prominent feature of all these systems is a small logarithmic increase in resistance with decreasing temperature at very low temperature. For reviews on the subject see references 1, 2 and 3. This non-metallic behavior may be explained theoretically, taking into account the presence of disorder, by invoking two different models: the first is weak-electron localization due to constructive quantum interference between elastically back-scattered electron waves (the usual Boltzmann transport theory neglects interference between the scattered electron waves); the second involves electron-electron many-body interactions which are enhanced in the presence of scattering on lattice static defects. Low magnetic field magnetoresistance measurements are the most widely used method to discriminate with some success between these two approaches. Indeed, the application of a low transverse magnetic field tends to suppress the weak-localization effect -and as a result produces negative magnetoresistance-, while the interaction model predicts no magnetoresistance.