Noncollinear ferromagnetism in (III,Mn)V semiconductors

We investigate the stability of the collinear ferromagnetic state in kinetic exchange models for (III,Mn)V semiconductors with randomly distributed Mn ions. Our results suggest that noncollinear ferromagnetism is common to these semiconductor systems. The instability of the collinear state is due to long-range fluctuations involving a large fraction of the localized magnetic moments. We address conditions that favor the occurrence of noncollinear ground states and discuss unusual behavior that we predict for the temperature and field dependence of its saturation magnetization.