Ferromagnet-semiconductor nanowire coaxial heterostructures grown by molecular-beam epitaxy

GaAs-MnAs core-shell structures are grown by molecular-beam epitaxy using wurtzite GaAs nanowires on GaAs (111) B. The nanowire structures curve due to the strain at the heterointerface when the substrate is not rotated during the growth, evidencing the diffusion length in the MnAs overgrowth being less than the perimeter of the columns. The MnAs growth is thus demonstrated to take place by direct deposition on the sidewall. The MnAs envelope is m -plane-oriented with the c -axis along the nanowire axis. The magnetic easy axis hence lies in the surface plane of the substrate, which is confirmed by magnetization measurements and magnetic-force microscopy.