Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 30: Postersitzung IV: Kritische Ph
änomene, Quantenstörstellen, niederdimensionale Systeme
TT 30.7: Poster
Donnerstag, 11. März 2004, 14:30–19:00, Poster A
The extended-Harris criterion and scale-free disorder in the 3D Anderson model of localization — •Macleans L. Ndawana1, Rudolf A. Römer1, and Michael Schreiber2 — 1University of Warwick, Department of Physics and Center for Scientific Computing, CV4 7AL, Coventry, United Kingdom — 2Institut für Physik, Technische Universität, D-09107 Chemnitz
We investigate the 3D Anderson model of localization [1] in the presence of scale-free [2] diagonal disorder via a modified transfer matrix method. The diagonal disorder is characterized by a correlation function that decays as r−α for separation r in the limit r → ∞ and α is the correlation-strength exponent. The extended-Harris criterion [3] is investigated by analyzing the dependence of the correlation-length critical exponent ν on α. We observe that for fixed W, there is a critical value αc below which, i.e. for α < αc, the universality class of the system changes. For α > αc, ν remains unchanged. This value of αc separates two regions, a region where correlations in disorder are relevant (α < αc) and a region where they are irrelevant (α > αc). Furthermore, we observe that at E=0, ν is independent of α. This might suggest that the metal-insulator transition at E=0 exhibits strong universality.
[1] P. W. Anderson, Phys. Rev. 109, 1492 (1958)
[2] H. A. Makse, et. al Phys. Rev. B 53, 5443 (1996)
[3] A. Weinrib and B. I. Halperin, Phys. Rev. B 27, 413 (1983)