Spin valve effect in self-exchange biased ferromagnetic metal/semiconductor heterostructures*

The systematic engineering of exchange biased ferromagnetic semiconductor spin valve devices is important for developing proof-of-concept semiconductor spintronics devices (such as spin torque oscillators). Here, we report magnetization and current-perpendicular-to-the-plane (CPP) magnetoresistance measurements in hybrid ferromagnetic metal/semiconductor heterostructures built from MnAs and (Ga,Mn)As [APL 91, 192503 (2007)]. We observe an exchange biased CPP spin valve effect in MnAs/(Ga,Mn)As bilayers, and discuss the dependence of the exchange field and the spin valve effect on (Ga,Mn)As layer thickness. We also demonstrate the CPP spin valve effect and exchange biasing in MnAs/ p-GaAs/ (Ga,Mn)As trilayers, and discuss the dependence of both phenomena on the doping and thickness of the non-magnetic spacer layer.