Giant anisotropy in x-ray magnetic linear dichroism in (Ga,Mn)As

Hugely anisotropic Mn L-2,L-3 x-ray magnetic linear dichroism (XMLD) is reported for the ferromagnetic semiconductor (Ga,Mn)As. The sign, magnitude, and line shape of the dichroism changes with azimuthal rotation of the samples between the in-plane < 110 > and < 100 > directions. The strong anisotropy is confirmed by multiplet calculations for a Mn 3d(5) configuration where charge anisotropy and magnetocrystalline anisotropy are absent. This allows a precise determination of the Mn 3d crystal-field splitting, and establishes the anisotropy in the XMLD as a general feature for localized moment systems with crystal-field symmetry.