Ferromagnetism and interlayer exchange coupling in short-period (Ga,Mn)As/GaAs superlattices

Magnetic properties of (Ga,Mn)As/GaAs superlattices are investigated. The structures contain magnetic (Ga,Mn)As layers, separated by thin layers of nonmagnetic GaAs spacer. The short-period Ga0.93Mn0.07As/GaAs superlattices exhibit a paramagnetic-to-ferromagnetic phase transition close to 60 K, for thicknesses of (Ga,Mn)As down to 23 A. For Ga0.96Mn0.04As/GaAs superlattices of similar dimensions, the Curie temperature associated with the ferromagnetic transition is found to oscillate with the thickness of nonmagnetic spacer. The observed oscillations are related to an interlayer exchange interaction mediated by the polarized holes of the (Ga,Mn)As layers.