Contribution from Ising domains overlapping out-of-plane to perpendicular magnetic anisotropy in Mn4N thin films on MgO(001)

• Published in: Journal of magnetism and magnetic materials Vol. 439; no. C; pp. 236 - 244
• Main Authors: Foley, Andrew, Corbett, Joseph, Khan, Alam, Richard, Andrea L., Ingram, David C., Smith, Arthur R., Zhao, Lianshui, Gallagher, James C., Yang, Fengyuan
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2017; Elsevier BV; Elsevier
• Subjects: Electron diffraction; Epitaxial growth; Ising model; Magnesium oxide; Magnetic anisotropy; Magnetic force microscopy; Magnetic thin films; Manganese anti-perovskite; Molecular beam epitaxy; Perpendicular magnetic anisotropy; Plane strain; Polarization; Superconductivity; Thin films; Molecular beam epitaxy; Perpendicular magnetic anisotropy; Magnetic force microscopy; Manganese anti-perovskite
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2017.03.079

•All significant components of perpendicular magnetic anisotropy are accounted for in ε-Mn4N thin films.•The scaling factor between tetragonal strain in ε-Mn4N and the strain component of anisotropy is quantified.•The most significant component is a large out-of-plane shape component attributed to a dipole-dipole interaction. Single phase ε-Mn4N thin and ultrathin films are grown on MgO(001) using molecular beam epitaxy. Reflection high-energy electron diffraction and out-of-plane X-ray diffraction measurements are taken for each sample in order to determine the in- and out-of-plane strain for each sample. Vibrating sample magnetometry and superconducting quantum interference device measurements, which are performed on the thin and ultrathin films respectively, are used to plot the magnetization of each sample versus both in- and out-of-planeH→-fields and to determine the magnitude of perpendicular magnetic anisotropy in these films. Three significant components of perpendicular magnetic anisotropy are observed in these films and are attributed to sample strain (1 component) and shape (2 components). Among these components, the most significant component 0.8–4.9Mergcm3 is identified as a second term of shape anisotropy, which possesses a negative linear relationship with sample thickness over the range from 9nm to 310nm. Atomic (magnetic) force microscopy measurements show the presence of a surface localized magnetic polarization (22–82%), which increases with decreasing thickness, when the net magnetizations of the films are zero. The second term of shape anisotropy as well as the surface localized polarization, which each depend on sample thickness, are each regarded as a consequence of Ising domains overlapping out-of-plane in these films.