Remarkable magnetic changes in hydrogenated Pd/Co/Mg thin film

Li-Jie Liaw^1*, Po-Chun Chang¹, Shi-Yu Liu¹, Fang-Yuh Loand¹, Wen-Chin Lin¹

¹Department of Physics, National Taiwan Normal University, Taipei, Taiwan

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

In previous years, the research of hydrogen absorption and storage were widely studied. In this study, our research focuses on magnesium, which is a hydrogen storage material owing to the favorable cost and high gravimetric and volumetric hydrogen densities. Because of the high-temperature characteristics of hydrogen absorption and desorption, magnesium is still not a usable material for storing hydrogen. In order to improve this, we used a palladium top layer to promote hydrogen diffusion into magnesium. The magnetism measurement of Pd/Co/Mg was conducted by magneto-optical Kerr effect (MOKE) under vacuum and 1 bar hydrogen pressure for comparison. The relation between coercivity and surface topography was confirmed with atomic force microscopy (AFM). The hydrogenation effect enhanced the magnetic coercivity from 25 Oe to 200 Oe irreversibly. More importantly, the change in surface roughness corresponds to magnetism after hydride. The crystal structure before and after hydrogenation were measured by X-ray diffraction (XRD). This research reveals for us to determine the correlation between storage hydrogen and the magnetic properties of Pd/Co/Mg thin films and will be valuable for future applications.

Keywords: magnetism, hydrogenation effect, surface topography