Planar Hall effect and uniaxial in-plane magnetic anisotropy in Mn δ -doped Ga As ∕ p − Al Ga As heterostructures

We have studied the planar Hall effect (PHE) in a Mn $\ensuremath{\delta}$-doped GaAs-based heterostructure consisting of Mn $\ensuremath{\delta}$-doped GaAs and $p$-type AlGaAs. We observe a distinct and large PHE and a specific in-plane [110] uniaxial magnetic anisotropy below the ferromagnetic transition temperature $({T}_{\mathrm{C}})$. This uniaxial in-plane magnetic anisotropy is found dominant over the biaxial cubic anisotropy, and is clearly identified by the angular dependence of PHE. This observation is quantitatively discussed in terms of two models of magnetization reversal: the coherent rotation model and the domain-wall motion model. The model calculation fit to the experimental data makes it possible to determine the uniaxial and cubic anisotropy fields and examine the behavior of magnetization reversal.