Structural and magnetic properties of ferrimagnetic ϵ-phase Mn₄N and antiferromagnetic ζ-phase Mn₁₀N thin films on MgO(001)

Single phase ϵ-Mn₄N and ζ-Mn₁₀N thin films are grown on MgO(001) using molecular beam epitaxy. The films are identified and characterized using reflection high-energy electron diffraction, x-ray diffraction, back scattered electron scanning electron microscopy, atomic/magnetic force microscopy and Rutherford backscattering spectrometry. These films are found to be highly smooth with root-mean-squared roughnesses 3.39 nm and below. The quality of ϵ-Mn₄N grown is strongly dependent on substrate temperature during growth. Epitaxial growth of substantial grains composed of the antiferromagnetic η-phase Mn₃N₂ side by side with ferrimagnetic ϵ-phase grains is observed when growth temperature is below 480°C. Ising domains isolated within areas roughly 0.5 μm across are observed in the ferrimagnetic ϵ-phase grains of samples consisting of a mix of η- and ϵ-phase grains. Magnetic domains following semi-continuous paths, which are 0.7-7.2 μm across, are observed in single phase ϵ-Mn₄N. Measurements of the ζ-phase detail the structure and magnetism of the material as high Mn content γ-type ζ-phase with a regular surface corrugation along the [100]-direction and antiferromagnetic.