Interlayer exchange coupling in MBE-grown GaMnAs-based multilayer systems

Interlayer exchange coupling (IEC) of GaMnAs-based multilayers has been investigated by varying the structural parameters, such as spacer thickness, carrier doping in the nonmagnetic layers, and repetition number of GaMnAs/GaAs bilayers. The type of IEC in the structure (i.e., either ferromagnetic or antiferromagnetic IEC) was identified from the magnetotransport measurements, which show either anisotropic magnetoresistance or giant magnetoresistance-like behavior. The investigation revealed that the parameters of the ferromagnetic GaMnAs layer (i.e., Mn composition and thickness) are less important than those of the non-magnetic GaAs spacer layer in the structure. In particular, it was found that the presence of carriers in the spacer layer plays a crucial role in determining the type and strength of the IEC in GaMnAs-based multilayer systems.