Epitaxial Ferrimagnetic Mn4N Thin Films on GaN by Molecular Beam Epitaxy

Direct epitaxial integration of magnetic layers with wide bandgap nitride semiconductors will enable spin-controlled transport and photonic phenomena, seeding ideas for functional spintronic devices. Using plasma-assisted molecular beam epitaxy (MBE) in a previously unexplored window, significantly improved ferrimagnetic Mn
₄
N layers are successfully grown on GaN with ~1 nm surface roughness. Distinct from earlier reports, the Mn
₄
N layers grown on GaN are found to be [001] oriented with 12-fold in-plane symmetry in the diffraction pattern. This unique epitaxial registry originates from three equivalent rotational domains. The ferrimagnetic magnetotransport properties of low growth temperature Mn
₄
N layers on GaN are comparable to those reported on cubic substrates such as MgO. However, a sign-flip of the Hall resistance is discovered for Mn
₄
N layers grown above 300 °C.