Comparison between the in-plane anisotropies and magnetostriction constants of thin epitaxial Fe films grown on GaAs and Ga_0.8In_0.2As substrates, with Cr overlayers

Thin epitaxial Fe films grown on GaAs(100) and Ga_0.8In_0.2As(100) substrates were investigated to determine how tuning the lattice constant mismatch between the Fe and the substrate may change the in-plane anisotropies and the magnetostriction. Two sets of Fe films were grown using molecular-beam epitaxy, each capped with a Cr overlayer. For each film, the in-plane anisotropy constants were determined from the normalized magnetization loops measured using a magneto-optic Kerr effect magnetometer. The lattice mismatch was found to give no contribution to the in-plane anisotropies. For all the films the magnetostriction constants, determined by the Villari method, were negative and became more negative as the Fe thickness decreased.