Magnetotransport study of temperature dependent magnetic anisotropy in a (Ga,Mn)As epilayer

The anisotropic magnetotransport properties of a (Ga,Mn)As epilayer and the magnetization switching are studied as a function of temperature. The magnetization switching field shows asymmetry for crystallographically equivalent [110] and [1̄10] directions at 4 K, and the asymmetry is more significant at 40 K. The magnetization switching features clearly show that cubic magnetocrystalline anisotropy along 〈100〉, which is biased by a small uniaxial anisotropy along the [110] easy axis, is dominant at 4 K. On the other hand, the [110] uniaxial anisotropy competes with the cubic anisotropy and dominates the magnetization switching at 40 K. Accordingly, the magnetization reversal in the (Ga,Mn)As epilayer occurs via 90° and 180° domain-wall displacement at 4 and 40 K, respectively. A mechanism of the change in the magnetic anisotropy is discussed within a theoretical description of the hole band structure.