Reentrant behavior and university in the Anderson transition

The three-dimensional Anderson model with a rectangular distribution of site disorder displays two distinct localization-delocalization transitions, against varying disorder intensity, for a relatively narrow range of Fermi energies. Such transitions are studied through the calculation of Localization lengths of quasi-one-dimensional systems by transfer-matrix methods, and their analysis by finite-size scaling techniques. For the transition at higher disorder we iind the localization-length exponent nu = 1.60(5) and the limiting scaled localization-length amplitude Lambda (0) =0.57(1), strongly suggesting universality with the transition at the band center, for which currently accepted values are nu =1.57(2) and Lambda (0) =0.576(2). For the lower (reentrant) transition, we estimate nu = 1.55(15) and Lambda (0) =0.55(5), still compatible with universality but much less precise, partly owing to significant finite-size corrections.