  We report the discovery of an effect where two ferromagnetic materials, one
semiconductor ((Ga,Mn)As) and one metal (permalloy), can be directly deposited
on each other and still switch their magnetization independently. We use this
independent magnetization behavior to create various resistance states
dependent on the magnetization direction of the individual layers. At zero
magnetic field a two layer device can reach up to four non-volatile resistance
states.
