Abstract
The Dzyaloshinskii-Moriya interaction (DMI) is responsible for exotic chiral and topological magnetic states such as spin spirals and skyrmions. DMI manifests at metallic ferromagnet/heavy-metal interfaces, owing to inversion symmetry breaking and spin-orbit coupling by a heavy metal such as Pt. Moreover, in centrosymmetric magnetic oxides interfaced by Pt, DMI-driven topological spin textures and fast current-driven dynamics have been reported, though the origin of this DMI is unclear. While in metallic systems, spin-orbit coupling arises from a proximate heavy metal, we show that in perpendicularly-magnetized iron garnets, rare-earth orbital magnetism gives rise to an intrinsic spin-orbit coupling generating interfacial DMI at mirror symmetry-breaking interfaces. We show that rare-earth ion substitution and strain engineering can significantly alter the DMI. These results provide critical insights into the origins of chiral magnetism in low-damping magnetic oxides and identify paths toward engineering chiral and topological states in centrosymmetric oxides through rare-earth ion substitution.
Highlights
The Dzyaloshinskii-Moriya interaction (DMI) is responsible for exotic chiral and topological magnetic states such as spin spirals and skyrmions
Mirror symmetry breaking at interfaces has been shown to give rise to an interfacial DMI in thin-film ferromagnets at room temperature, providing a general route to tailor chirality in magnetic materials through interface engineering14,15. iDMI is typically observed in metallic ferromagnet/heavy-metal (HM) bilayers, where strong spin-orbit coupling (SOC) in the HM is responsible for generating the iDMI14–17
We find that the origin of the DMI is interfacial, and that in substrate/REIG/metal trilayers, both the substrate and the metal overlayers contribute to the strength of the DMI
Summary
The Dzyaloshinskii-Moriya interaction (DMI) is responsible for exotic chiral and topological magnetic states such as spin spirals and skyrmions. Experimental observations of homochiral Néel DWs23,24,26 and topological Hall-like signals[27,28] in thin-film rare-earth (RE) iron garnets (REIGs) at room temperature suggest that spin–orbit-driven phenomena thought to be restricted to metallic systems might manifest more broadly in insulating magnetic oxides. We further show that the iDMI can be tuned by substrate strain, by at least a factor of two, providing a powerful means to tune chiral magnetism in oxide materials These results suggest that introducing SOC in magnetic oxides through RE ion substitution can provide a general path toward realizing topological spin states in thin films and heterostructures, opening a new door for oxide-based spintronics
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