2007/10/31 by Donald Priour, D. J. Priour Jr, S. Das Sarma · 13 citations
Materials Science · Physics and Astronomy · Psychology · #Chemical and Physical Properties of Materials #Condensed matter physics #Physics #Psychology #Quantum mechanics #Semiconductor #Surface and Thin Film Phenomena #Theoretical and Computational Physics #cond-mat.dis-nn #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.81.224403
published in Physical Review B 81(22) (American Physical Society) · 11 pages, 9 figures
arxiv created 2010/04/08 · openalex publication_date 2010/06/01 · arxiv updated 2010/06/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Using large-scale Monte Carlo calculations, we consider strongly disordered Heisenberg models on a cubic lattice with missing sites (as in diluted magnetic semiconductors such as Ga_1\ensuremath-xMnxAs). For disorder ranging from weak to strong levels of dilution, we identify Curie temperatures and calculate the critical exponents \ensuremathν, \ensuremathγ, \ensuremathη, and \ensuremathβ; we find, per the Harris criterion, good agreement with critical indices of the pure Heisenberg model where there is no disorder component. Moreover, we find that thermodynamic quantities (e.g., the second moment of the magnetization per spin) self-average at the ferromagnetic transition temperature with relative fluctuations tending to zero with increasing system size. We directly calculate effective critical exponents for T>Tc, yielding values which may differ significantly from the critical indices for the pure system, especially in the presence of strong disorder. Ultimately, the difference is only apparent, and eventually disappears when T is very close to Tc.