Effects of film thickness and annealing on the magnetic properties of GaMnAsP ferromagnetic semiconductor

Abstract

We have investigated the magnetic properties of ferromagnetic semiconductor GaMnAsP films with two different thicknesses. Temperature scans of the resistance revealed that the Curie temperature was higher in the 50-nm GaMnAsP layer than in the 16-nm layer, and was increased in both layers after annealing. The Hall effect was measured during the magnetization reversal process to identify the anisotropy of the films. The hysteresis observed from the as-grown samples in anomalous Hall resistance measurements implied the presence of out-of-plane magnetic anisotropy in both samples. The out-of-plane magnetic anisotropy in both samples became much stronger after thermal annealing. Quantitative values of the magnetic anisotropy of the GaMnAsP films were obtained from angular dependent Hall effect measurements. By constructing magnetic anisotropy energy diagrams for the films, we clearly show the change of magnetic anisotropy depending on the film thickness and thermal annealing in GaMnAsP films.