Underlayer catalytic effect on hydrogen-induced modulation of ferromagnetism

Abstract

The modulation of magnetic properties via chemical state control, particularly using hydrogen (H2), has attracted attention in spintronics. In this study, we investigate the underlayer catalytic effect on the H2-induced modulation of the ferromagnetic (FM) state in a FM thin film/oxide layered system. In a Co/MgO structure with Pt and Au underlayers, H2-annealing restores the magnetization of deeply oxidized Co layers only in Pt underlayer samples, while no restoration occurs in Au underlayer samples. XPS measurements clarify that the chemical state of the Co layer is significantly altered in the Pt-sample after H2-annealing, indicating that the reduction of oxidized Co is caused by the strong catalytic action of Pt. Furthermore, we found that the H2-induced restoration of the FM state occurs even at room temperature, and it is more pronounced when the sample size is reduced. These findings not only highlight the significant role of the catalytic effects in the hydrogen-induced modulation of magnetic properties but also provide the possibility of exploring the mechanism of the catalytic effect using spintronics devices.