Spin reorientation transition in single-domain (Ga,Mn)As

We demonstrate that the interplay of in-plane biaxial and uniaxial anisotropy fields in (Ga, Mn)As results in a spin reorientation transition and an anisotropic ac susceptibility which is fully consistent with a simple single-domain model. The uniaxial and biaxial anisotropy constants vary, respectively, as the square and fourth power of the spontaneous magnetization across the whole temperature range up to T-C. The weakening of the anisotropy at the transition may be of technological importance for applications involving thermally assisted magnetization switching.