Origins of magnetic anisotropies in ferromagnetic thin films studied by angle-dependent XMCD

Speaker: Atsushi Fujimori; Department of Physics, University of Tokyo
Date & Time: 4/4/2018 11:00 AM
Location: BRIM 311
Local Contact: George Sawatzky
Intended Audience:

Magnetic anisotropy is one of the most important properties of ferromagnetic materials, and is usually attributed to the anisotropy of orbital magnetic moment, known as the Bruno model. However, additional contributions from the anisotropic distribution of spin-polarized electrons, represented by the ‘magnetic dipole’, may become significant when spin-orbit coupling becomes non-negligible. In order to reveal the origin of magnetic anisotropy in magnetic thin films, we have measured x-ray magnetic circular dichroism (XMCD) with varying magnetic-field direction, including the longitudinal geometry, where spin contribution vanishes and orbital contribution can be extracted. Results will be presented for Fe-Pt alloy thin films known for their strong perpendicular magnetic anisotropy [1], transition-metal oxide thin films whose magnetic anisotropy is controlled by epitaxial strain and film thickness [2]. [1] K. Ikeda et al., Appl. Phys. Lett. 111, 142402 (2017). [2] G. Shibata et al., npj Quantum Mater. 3, 3 (2018); Y. Nonaka et al., to be submitted.