Controllable Perpendicular Magnetic Anisotropy in Fe/Fe100−xRhx Heterostructures Probed by Ferromagnetic Resonance

A ferromagnetic-antiferromagnetic (FM-AFM) thin-film heterostructure is proposed to be a potential system that can induce perpendicular magnetic anisotropy (PMA) in a ferromagnet, although there are few material combinations available and the underlying mechanism is not sufficiently understood. Here, we demonstrate that the AFM phase of an $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Rh}$ ordered alloy induces PMA in an adjacent $\mathrm{Fe}$ layer in an $\mathrm{Fe}/\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Rh}$ heterostructure, which manifests itself as an additional mode of ferromagnetic resonance. The induced interfacial PMA disappears following a magnetic phase transition of $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Rh}$ from the AFM to the FM state, suggesting that the AFM order is crucial for the stabilization of PMA. The absence of the additional resonance mode in an $\mathrm{Fe}/\mathrm{Rh}/\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Rh}$ control sample suggests that the PMA originates from a magnetic exchange coupling at the $\mathrm{Fe}/\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Rh}$ interface. The results are promising for the development of high-density spintronic devices, in which PMA is controllable through the phase transition of $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Rh}$.