Chiral coupling of two orthogonal magnetizations in a single ferrimagnetic GdCo layer

Understanding chiral coupling is an important topic in spintronics as it offers potential applications in domain wall- or skyrmion-based magnetic memory or logic devices. In this study, we investigate chiral coupling in a single-layer ferrimagnetic GdCo film with in-plane magnetic anisotropy. We observe the emergence of local out-of-plane magnetization within this layer, and importantly, we find that these two orthogonal magnetizations are chirally coupled, which is verified by the shift of the hysteresis loop depending on the initial chiral configuration of magnetic moments. Through scanning transmission electron microscopy and electron energy loss spectroscopy, we reveal that the elemental inhomogeneity in the lateral direction and a gradual decrease in the GdCo composition ratio in the vertical direction contribute to the generation of a non-vanishing out-of-plane magnetic moment and its chiral coupling with the in-plane moment via the bulk Dzyaloshinskii-Moriya interaction. Our findings demonstrate that chiral coupling can facilitate diverse magnetic configurations, even within a single-layer ferrimagnet, thereby expanding the potential of the ferrimagnet as the platform for investigating topological magnetic textures.