Epitaxial Growth and Magnetic Properties of NiMnAs Films on GaAs Substrates

Single-phase Ni0.46Mn0.54As films with strained C1b symmetry have been successfully grown on GaAs (001) substrates by molecular-beam epitaxy. The epitaxial relationship between the film and the substrate has been studied using synchrotron radiation, and a preferred configuration of (110)-orientated Ni0.46Mn0.54As on (001)-orientated GaAs was revealed. In addition, the magnetic properties of the films were found to be significantly influenced by the growth temperature. The optimized growth temperature is determined to be ~370 degree Celsius , for which relatively high Curie temperature, large saturation magnetization and coercive field, as well as the pronounced in-plane magnetic anisotropy were obtained. According to the results of X-ray absorption spectroscopy, the above phenomenon can be attributed to the variation of the local electronic structure of the Mn atoms. Our work provides useful information for the further investigations of NiMnAs, which is theoretically predicted to host robust half-metallicity.