Sensitive hydrogenation effect on magnetic behavior of CoPd alloy thin films

Pd has long been used as a high efficient catalyst for hydrogen dissociation and absorption. Pd thin films of few nm thickness are widely used in metal-hydride systems. In the Pd-alloys, the hydroge-nation of Pd may easily bring in proximity effect upon the underneath functional materials. This effect is important from fundamental point of view and also applicable in future techniques. Besides of hydrogen catalyst, in spintronics´s point of view, Pd is also a key element for memory storage. The strain and magnetostriction effect in Co, Fe-Pd alloy films dominate the magnetoelastic anisot-ropy and yield the perpendicular magnetization, which can significantly increase the memory density. Thus Pd is a multifunctional element for the devices or sensors applicable in both spintron-ics and energy applications. In our experiment, Co-Pd alloy thin films of different alloy compositions were prepared for the investigation of reversible hydrogenation effect on the magnetic and optical properties. As shown in Fig. 1, after hydrogenation the magnetic coercivity (Hc) was and the squareness of hysteresis loops (i.e. remanence/saturation) were significantly modified. The hydrogenation effects varies with the alloy composition, from Co-rich to Pd-rich. The detailed comparison was discussed in this report.