Control of magnetic anisotropy in (Ga,Mn)As with etching depth of specimen boundaries

► A large mechanical effect on the magnetic anisotropy in (Ga,Mn)As is found. ► The mechanical effect appears in samples with comparatively large sizes. ► The uniaxial magnetic anisotropy in (Ga,Mn)As disappears with lattice relaxation. ► The result is against a dimerization model for the magnetic anisotropy. ► The result is not against the Zener mechanism of the ferromagnetism.