Microstructure, magnetic and electronic transport properties of reactively facing-target sputtered epitaxial Mn₄N films

The structure, magnetic and electronic transport properties of epitaxial Mn₄N films fabricated by the facing-target reactive sputtering method have been investigated systematically. The high-quality growth of Mn₄N films was confirmed by x-rayθ-2θ, pole figures and high-resolution transmission electron microscopy. The Mn₄N films exhibit ferrimagnetic with strong perpendicular magnetic anisotropy. The saturation magnetization of Mn₄N films decreases with increasing temperature, following the Bloch's spin wave theory. The resistivity of Mn₄N films exhibits metallic conductance mechanism. Debye temperature of Mn₄N is estimated to be 85 K. The calculated residual resistivityρ_xx0of the 78.8 nm-thick Mn₄N film is 30.56μΩ cm. The magnetoresistances of Mn₄N films display a negative signal and butterfly shape. The sign of anisotropic magnetoresistance (AMR) is positive, which infers that the AMR is dominated by the spin-up conduction electrons. Moreover, the transformation of fourfold to twofold symmetry for AMR and twofold to onefold symmetry for planar Hall resistivity is attributed to tetragonal crystal field effect.