In-plane uniaxial magnetic anisotropy in (Ga, Mn)As due to local lattice distortions around Mn2+ ions

We theoretically investigate the interplay between local lattice distortions around the Mn2+ impurity ion and its magnetization, mediated through spin–orbit coupling of holes. We show that the tetrahedral symmetry around the Mn2+ ion is spontaneously broken and that local Jahn–Teller distortions coupled with growth strain result in uniaxial magnetic anisotropy. We also account for the experimentally observed in-plane uniaxial magnetic anisotropy rotation due to variation of hole density. According to this model, lack of inversion and top-down symmetries of (Ga, Mn)As layers lead to in-plane biaxial symmetry breaking in the presence of Jahn–Teller distortions. (paper)