Epitaxial Growth and Magnetic Properties of NiMnAs Films on GaAs Substrates

Single-phase Ni_0.92Mn_1.08As films with strained C_\rm 1b symmetry are grown on GaAs (001) substrates. In addition, a preferred epitaxial configuration of (110)-orientated Ni_0.92Mn_1.08As on (001)-orientated GaAs is revealed by synchrotron radiation measurement. The magnetic properties of the films are found to be significantly influenced by the growth temperature and the optimized growth temperature is determined to be \sim370^\circ\!C. According to the results of x-ray absorption spectroscopy, these phenomena 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 a theoretically predicted half-metal.