Crystal structures of hexagonal MnAs ferromagnetic epilayers grown on GaAs (100) substrates

Abstract

Hexagonal MnAs thin films were grown on GaAs (100) substrates by using molecular beam epitaxy. The magnetization curve as a function of the magnetic field at 5 K showed that the MnAs thin films were ferromagnetic, and the magnetization curve as a function of the temperature revealed that the ferromagnetic transition temperature was as high as 318 K. The selected-area electron-diffraction pattern (SADP) and the high-resolution transmission electron microscopy (HRTEM) measurements on the MnAs/GaAs heterostructure showed that the hexagonal MnAs layer was grown pseudomorphically on the GaAs substrate. Based on the SADP and HRTEM results, a possible crystal structure for the MnAs/GaAs heterostructure is presented.