Longitudinal and perpendicular exchange bias in (Mn,Co)3Ga/Mn3Ga with tunable magnetic anisotropy

초록

The exchange bias (EB) effect plays a pivotal role in spintronic devices and is governed by the interfacial spin configurations between ferromagnetic (FM) and antiferromagnetic (AFM) layers, but the underlying mechanism is still unveiled. While most progress has been made in understanding longitudinal exchange bias (LEB) in FM/AFM systems, studies on perpendicular exchange bias (PEB) remain limited. In this study, we investigated the EB effects in Mn<inf>3-x</inf>Co<inf>x</inf>Ga/Mn<inf>3</inf>Ga bilayers, composed of ferrimagnetic (FI) Mn<inf>3-x</inf>Co<inf>x</inf>Ga and AFM Mn<inf>3</inf>Ga layers, offering tunable magnetic anisotropy and interfacial spin configurations. Mn<inf>3-x</inf>Co<inf>x</inf>Ga exhibits a transition from a hard FI phase with perpendicular magnetic anisotropy (x = 0.12) to a soft FI phase with in-plane magnetic anisotropy (x = 0.57). The spin configuration of Mn<inf>3</inf>Ga layer is further manipulated through field-cooling direction. This approach enabled a comparative study of LEB and PEB effects. The EB effect was most pronounced in orthogonal spin configurations at the interfaces: PEB for x = 0.12 under an in-plane field and LEB for x = 0.57 under an out-of-plane field. These results provide critical insights into the role of interfacial spin configurations in the EB effect to advance the understanding of EB mechanisms in magnetic multilayers. © 2025 Elsevier B.V.

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