Structural and magnetic properties of MBE-grown GeMnN2 thin films

Epitaxial GeMnN2 thin films are synthesized by plasma-assisted molecular beam epitaxy. Transmission electron microscopy and x-ray diffraction measurements confirm that it is the orthorhombic variant, consistent with the predictions of first-principles calculations. The magnetic properties of the films are related to defects, with samples grown under Ge-rich conditions exhibiting a net magnetic moment above room temperature. These results are explained by first-principles calculations, indicating that the preferential substitution of one magnetic sublattice of GeMnN2 by impurities and/or intrinsic defects such as Ge antisites produces a net magnetic moment in an antiferromagnetic background, and also introduces spin-polarized carriers near the Fermi level.