Anomalous Metallic Behavior in Strongly Correlated Electron Systems with Disorder

We study several aspects of the behavior of strongly correlated electron systems with disorder. First we examine the influence of strong electron-electron interactions on the impurity dominated resistivity. In the weak-coupling limit, the resistivity is reduced by the screening effect which is determined by the charge compressibility, which is proportional to the inverse screening length. We show that when strong correlations are present, although the compressibility is reduced, the screening effect is nevertheless strongly enhanced. This phenomenon is traced to the non-perturbative Kondo-like processes captured by dynamical mean field theory, but which are absent in weak coupling approaches. We discuss a possible relevance of our results for the physics of high mobility MOSFETs. In the second part of the thesis we study possible mechanisms of disorder-driven non-Fermi liquid behavior in heavy fermion systems. We present simple analytical arguments explaining the universal emergence of electronic Griffiths phases as precursors of disorder-driven metal-insulator transitions in correlated electronic systems. Then we examine the interplay of the Kondo effect and the RKKY interactions in electronic Griffiths phases using extended dynamical mean-field theory methods. We find that sub-Ohmic dissipation is generated for sufficiently strong disorder, leading to suppression of Kondo screening on a finite fraction of spins, and giving rise to universal spin-liquid behavior.