Thermally modulated hydrogenation in FexPd1-x alloy films: Temperature-driven peculiar variation of magnetism

The sensitive hydrogen effect on spintronic materials has been recently demonstrated to have high application potential. However, the correlation between hydrogen pressure (P-H2), temperature, and magnetic properties still remains unclear. In this study, the magnetic moment of Fe in an Fe-Pd alloy thin film was increased through hydrogen absorption, as evidenced by the enhanced x-ray magnetic circular dichroism signal of Fe. Hydrogen absorption and desorption hysteresis loops in the magnetic coercivity H-c-P-H2 diagram revealed that most hydrogen was absorbed when P-H2 was above 10 mbar and desorbed when P-H2 was approximately 10(-6) mbar. The hydrogenation effect on the magnetism of an Fe-Pd alloy film was eliminated at an annealing temperature of 360K without considerable hydrogen desorption. The annealing-driven cyclic enhancement of H-c was demonstrated because of the competition between thermal activation and H bonding. These results clearly reveal the critical temperature dependence and provide applicable knowledge of the hydrogenation effect on magnetic Pd-alloys. Published under license by AIP Publishing.