Abstract
Perpendicular magnetization is essential for high-density memory application using magnetic materials. High-spin polarization of conduction electrons is also required for realizing large electric signals from spin-dependent transport phenomena. The Heusler alloy is a well-known material class showing the half-metallic electronic structure. However, its cubic lattice nature favors in-plane magnetization and thus minimizes the perpendicular magnetic anisotropy (PMA), in general. This study focuses on an inverse-type Heusler alloy, (MCG), with a small off-stoichiometry (), which is expected to be a half-metallic material. We observed a relatively large uniaxial magnetocrystalline anisotropy constant () of the order of J/ at room temperature in MCG films with a small tetragonal distortion of a few percent. A positive correlation was confirmed between the ratio of lattice constants and . Imaging of magnetic domains using Kerr microscopy clearly demonstrated a change in the domain patterns along with . X-ray magnetic circular dichroism (XMCD) was employed using a synchrotron radiation soft x-ray beam to get insight into the origin of PMA. Negligible angular variation of orbital magnetic moment () evaluated using the XMCD spectra suggested a minor role of the so-called Bruno's term to . Our first-principles calculation reasonably explained the small and the positive correlation between the ratio and . The origin of the magnetocrystalline anisotropy was discussed based on the second-order perturbation theory in terms of the spin-orbit coupling, claiming that the mixing of the occupied - and the unoccupied -spin states is responsible for the PMA of the MCG films.
10 More- Received 1 November 2021
- Revised 8 February 2022
- Accepted 4 March 2022
DOI:https://doi.org/10.1103/PhysRevMaterials.6.044405
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