Carrier-density dependence of magnetic and magneto-optical properties of (Ga,Mn)As

We studied the magnetic properties and the magnetic circular dichroism (MCD) of (Ga,Mn)As films with two kinds of the hole-carrier density though keeping a constant value in the Mn concentration grown by the molecular beam epitaxy method. To control the carrier density in (Ga,Mn)As, we utilized Sn atoms, which compensate the hole carriers intrinsically doped due to substitution of Mn2+ atoms for Ga. The magnitude and the spectral shape of the MCD and the magnetic order have shown remarkable dependence on the hole-carrier density. The observed MCD and normal absorption spectral changes depending on the hole-carrier density can be explained by the model proposed by Szczytko which includes the effects of the disorder and the change in the Fermi energy level.