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Interface-driven chiral magnetism and current-driven domain walls in insulating magnetic garnets

Abstract

Magnetic oxides exhibit rich fundamental physics1,2,3,4 and technologically desirable properties for spin-based memory, logic and signal transmission5,6,7. Recently, spin–orbit-induced spin transport phenomena have been realized in insulating magnetic oxides by using proximate heavy metal layers such as platinum8,9,10. In their metallic ferromagnet counterparts, such interfaces also give rise to a Dzyaloshinskii–Moriya interaction11,12,13 that can stabilize homochiral domain walls and skyrmions with efficient current-driven dynamics. However, chiral magnetism in centrosymmetric oxides has not yet been observed. Here we discover chiral magnetism that allows for pure spin-current-driven domain wall motion in the most ubiquitous class of magnetic oxides, ferrimagnetic iron garnets. We show that epitaxial rare-earth iron garnet films with perpendicular magnetic anisotropy exhibit homochiral Néel domain walls that can be propelled faster than 800 m s−1 by spin current from an adjacent platinum layer. We find that, despite the relatively small interfacial Dzyaloshinskii–Moriya interaction, very high velocities can be attained due to the antiferromagnetic spin dynamics associated with ferrimagnetic order.

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The data that support the findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

This work was supported by the DARPA TEE program. The authors thank L. Liu for use of ion milling equipment. C.O.A. thanks A. Jun Tan for discussions.

Author information

C.O.A., C.A.R. and G.S.D.B. conceived the project and planned the experiments. E.R. synthesized and characterized the TmIG and TbIG samples. C.O.A. deposited the metal layers and micro-fabricated the domain wall tracks. C.O.A., L.C., M.M., C.M. and D.B. prepared the experimental set-up. C.O.A. and L.C. performed the measurements. L.C. and F.B. modelled the domain wall dynamics. C.O.A. and G.S.D.B. analysed the data and wrote the manuscript. All authors contributed to the discussion of the data in the manuscript and Supplementary Information.

Competing interests

The authors declare no competing interests.

Correspondence to Geoffrey S. D. Beach.

Supplementary information

Supplementary Information

Supplementary Sections 1,2, Supplementary Figure 1, Supplementary References 1–9

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Further reading

Fig. 1: Experimental set-up and current-induced magnetization reversal.
Fig. 2: Field-driven DW dynamics.
Fig. 3: Current-assisted depinning and DW propagation.
Fig. 4: Measuring chiral exchange fields for various rare-earth garnets and interfaces.
Fig. 5: Current-driven DW velocity.