Anisotropic strain relaxation of thin Fe film on c(4×4) reconstructed GaAs (0 0 1) surface

We report the interplay between the anisotropic strain relaxation and the in-plane uniaxial magnetic anisotropy in a 5 nm Fe film grown on GaAs (0 0 1) by molecular-beam epitaxy. Tetragonal distortion and in-plane anisotropic strain relaxation were accurately measured by synchrotron X-ray diffraction. A stronger coherence at the interface between Fe and GaAs is also observed in the annealed film. A competing model including magnetocrystalline anisotropy, interface anisotropy, and magnetoelastic anisotropy is proposed to characterize the in-plane magnetic anisotropy.