Exchange Biasing of the Ferromagnetic Semiconductor Ga_1-xMn_xAs

We demonstrate the exchange coupling of a ferromagnetic semiconductor (Ga1−xMnxAs) with an overgrown antiferromagnet (MnO). Unlike most conventional exchange biased systems, the blocking temperature of the antiferromagnet (TB=48±2K) and the Curie temperature of the ferromagnet (TC=55.1±0.2K) are comparable. The resulting exchange bias manifests itself as a clear shift in the magnetization hysteresis loop when the bilayer is cooled in the presence of an applied magnetic field and an enhancement of the coercive field.