Control of coercivities in (Ga,Mn)As thin films by small concentrations of MnAs nanoclusters

We demonstrate that low concentrations of a secondary magnetic phase in (Ga,Mn)As thin films can enhance the coercivity by factors up to ∼100 without significantly degrading the Curie temperature or saturation magnetization. Magnetic measurements indicate that the secondary phase consists of MnAs nanoclusters, of average size ∼7nm. This approach to controlling the coercivity while maintaining a high Curie temperature may be important for realizing ferromagnetic semiconductor based devices.