Anderson Metal-Insulator Transitions With Classical Magnetic Impurities

Daniel Jung, Keith Slevin, Stefan Kettemann

Published 2015-07-13Version 1

We study the effects of classical magnetic impurities on the Anderson metal-insulator transition numerically. We find that a small concentration of Heisenberg impurities enhances the critical disorder amplitude $W_{\rm c}$ with increasing exchange coupling strength $J$ due to time-reversal symmetry breaking. The resulting scaling with $J$ is analyzed which supports an anomalous scaling prediction by Wegner due to the additional spin-rotational symmetry breaking. The results are obtained by a finite-size scaling analysis of the geometric average of the local density of states. The latter can efficiently be calculated by means of the kernel polynomial method. We discuss the relevance of our findings for systems like phosphor-doped silicon, which exhibit a metal-insulator transition driven by both interaction and disorder, accompanied by the presence of magnetic moments.