Depth profile of the tetragonal distortion in thick GaMnAs layers grown on GaAs by Rutherford backscattering/channeling

We provide a direct measurement of the tetragonal distortion in thick GaMnAs as a function of depth by Rutherford backscattering combining with channeling. The thick GaMnAs film is tetragonally strained and the tetragonal distortion is found to be depth independent. Our finding excludes strain relaxation as the origin of the uniaxial in-plane magnetic anisotropy observed in GaMnAs.