DISORDER AND FRUSTRATION IN DILUTED MAGNETIC SEMICONDUCTORS AT LOW CARRIER DENSITIES

Abstract

We examine the effects of positional disorder of the magnetic ion in III-V Diluted Magnetic Semiconductors such as ( Ga , Mn ) As at low carrier densities on the nature of the low-temperature ordered magnetic state, using numerical mean field and Monte Carlo methods. We find that positional disorder leads to a highly inhomogeneous ferromagnetic order in the low carrier density limit, with unusual thermodynamic and magnetic behavior. Spin-orbit coupling presented in the valence band leads to frustration in the hole-doped system, but does not significantly affect the low temperature magnetization.