Highly Stable, Antiferromagnetic MnN Films Grown by Molecular Beam Epitaxy

High-quality antiferromagnetic (AFM) θ-phase manganese nitride (MnN) films were successfully grown on MgO (001) substrates by plasma-assisted molecular beam epitaxy. Structural analysis confirms the high-quality MnN film has a tetragonal distortion with a c/a ratio of ~ 0.98. The film exhibits exceptional stability in both aqueous and ambient conditions, which is a crucial factor for practical applications. Electrical transport reveals its metallic behavior with an upturn at low temperatures, which could be attributed to the Kondo effect originated from nitrogen vacancy-induced magnetic impurities. Room temperature exchange bias has been demonstrated in a MnN/CoFeB heterostructure, verifying the AFM ordering of MnN. Considering its high Néel temperature ~ 650 K, superior stability, and low-cost, this work highlights the epitaxial MnN films as a promising candidate for AFM spintronic applications.