Hydrogenation-mediated lateral spin-reorientation transition in FePd thin films

Li-Jie Liaw^1*, Po-Chun Chang¹, Yu-Chun Wang¹, Po-Wei, Chen¹, Zi-Qi Liu¹, Yu-Tso Liao¹, Tzu-Hung Chuang², Der-Hsin Wei², Ming-Yau Chern³, Fang-Yuh Lo¹, Wen-Chin Lin¹

¹Department of Physics, National Taiwan Normal University, Taipei, Taiwan
²National Synchrotron Radiation Research Center, Hsinchu, Taiwan
³Department of Physics, National Taiwan University, Taipei, Taiwan

* Presenter:Li-Jie Liaw, email:lijiedrum@gmail.com

In recent decades, the application of palladium-assisted hydrogenation in magnetism was extensively studied. Most of the previous studies focus on the FePd crystalline structure of L1₀ phase with perpendicular magnetic anisotropy (PMA). In contrast to the crystalline-induced magnetic anisotropy energy (MAE), we focused on the hydrogen-induced rotation of MAE in FePd alloy thin films. The magnetic properties were measured either in a vacuum or under 1 bar hydrogen pressure using magneto-optical Kerr effect (MOKE). The magnetic easy axis was rotated from 170 degree to 90 degree after the hydrogenation. The magnetic moment of Fe in FePd alloy thin film was increased through hydrogen absorption, as evidenced by the enhanced x-ray magnetic circular dichroism (XMCD). The crystal structure of hydrogen-sensitive and hydrogen-insensitive magnetic film was characterized by X-ray diffraction (XRD). According to the cross-sectional transmission electron microscope (TEM) analysis and the depth-dependent analysis of magnetism, we conclude that the rotation of MAE originates from the competition between the interfacial strain-induced MAE and oblique deposition-induced surface microstructure. This report reveals the correlation between hydrogen charge and the magnetism of FePd alloy film and will be valuable for future applications.

Keywords: magnetic anisotropy energy, hydrogenation effect, crystalline structure