Berlin 2015 – wissenschaftliches Programm
TT 71.24: Poster
Mittwoch, 18. März 2015, 15:00–18:00, Poster B
Impact of Local Magnetic Moments on the Anderson Metal-Insulator Transition — •Daniel Jung1, Keith Slevin2, and Stefan Kettemann1 — 1School of Engineering and Science, Jacobs University Bremen gGmbH, Campus Ring 1, 28759 Bremen, Germany — 2Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
We study the effects of classical magnetic impurities on the Anderson metal-insulator transition numerically. In particular we find that while a finite concentration of Ising impurities lowers the critical value of the site-diagonal disorder amplitude Wc, in the presence of Heisenberg impurities, Wc is first enhanced with increasing exchange coupling strength J due to time-reversal symmetry breaking. The resulting scaling with J is analyzed and compared to analytical predictions by Wegner . The results are obtained numerically, based on a finite-size scaling procedure for the typical density of states, which is the geometric average of the local density of states. The latter can efficiently be calculated using the kernel polynomial method (KPM). We extend previous approaches by combining the KPM with a finite-size scaling analysis. We also discuss the relevance of our findings for systems like phosphor-doped silicon, which are known to exhibit a quantum phase transition from metal to insulator driven by the interplay of both interaction and disorder, accompanied by the presence of a finite concentration of magnetic moments.
 F. Wegner, Nucl. Phys. B 280, 210 (1987).