GaMnAs on InGaAs templates: Influence of strain on the electronic and magnetic properties

We present a systematic study on the influence of strain on the electronic and magnetic properties of GaMnAs. A series of GaMnAs layers was grown on relaxed InGaAs/GaAs templates, enabling us to vary the strain in the GaMnAs layers continuously from tensile to compressive, including unstrained samples. The as-grown GaMnAs layers showed no apparent dependence of hole density and Curie temperature on strain, whereas a systematic linear variation of the uniaxial out-of-plane magnetic anisotropy was found. From compressive to tensile strain, the out-of-plane direction gradually undergoes a transition from a magnetic hard axis to a magnetic easy axis. Low-temperature post-growth annealing leads to an increase in hole density and a decrease of the relaxed lattice parameter of GaMnAs, resulting in a pronounced enhancement of the uniaxial out-of-plane anisotropy.