Hydrogen-Controlled Spin Reorientation Transition in a Nanometer-Thick FePd Layer on Co/[Pt/Co]₄/Pt Multilayers for Applications in Spintronics

In this study, we deposited a hydrogen-sensitive FePd alloy film on Co/[Pt/Co] 4 /Pt multilayers with perpendicular magnetic anisotropy (PMA). Through hydrogenation, spin-reorientation transition (SRT) from a perpendicular to an in-plane direction was observed in the 2-nm-thick FePd capped multilayer. Magneto-optic Kerr effect measurements were performed in hydrogen gas at pressures ranging from a vacuum of 5 × 10 –3 mbar to H 2 gas at 200 mbar. Reversible SRT was demonstrated with the cyclic change of H 2 pressure. Furthermore, tuning the strength of the PMA multilayer by adjusting the thickness of the Pt layer changed the SRT-critical thickness of the FePd cap and the hydrogen-induced SRT behavior. These findings will be valuable for application in spintronics through the electronic control of H-migration.