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Ferroelectrically tunable magnetic skyrmions in ultrathin oxide heterostructures

Abstract

Magnetic skyrmions are topologically protected whirling spin texture. Their nanoscale dimensions, topologically protected stability and solitonic nature, together are promising for future spintronics applications. To translate these compelling features into practical spintronic devices, a key challenge lies in achieving effective control of skyrmion properties, such as size, density and thermodynamic stability. Here, we report the discovery of ferroelectrically tunable skyrmions in ultrathin BaTiO3/SrRuO3 bilayer heterostructures. The ferroelectric proximity effect at the BaTiO3/SrRuO3 heterointerface triggers a sizeable Dzyaloshinskii–Moriya interaction, thus stabilizing robust skyrmions with diameters less than a hundred nanometres. Moreover, by manipulating the ferroelectric polarization of the BaTiO3 layer, we achieve local, switchable and nonvolatile control of both skyrmion density and thermodynamic stability. This ferroelectrically tunable skyrmion system can simultaneously enhance the integratability and addressability of skyrmion-based functional devices.

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Fig. 1: Ferroelectric proximity effect and the DMI at the BTO/SRO interface.
Fig. 2: Topological Hall effects of BTO/SRO/SrTiO3(001) heterostructures.
Fig. 3: Magnetic force microscopy of magnetic skyrmions in the B20S5 sample.
Fig. 4: FE control of skyrmion properties.
Fig. 5: Scanning transmission electron microscopy results near the BTO/SRO interface.

Data availability

All relevant data that support the plots within this paper are available from the corresponding author upon reasonable request.

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Acknowledgements

Q.L., W.M. and Q.F. were supported by the National Key R&D Program of China (grants no. 2017YFA0402903 and no. 2016YFA0401003) and the National Natural Science Foundation of China (grant no. 51627901). J.H.H. was supported by Samsung Science and Technology Foundation under Project Number SSTF-BA1701-07. STEM and PPMS measurements were supported by the National Center for Inter-University Research Facilities (NCIRF) at Seoul National University in Korea. All the authors want to acknowledge major support from the Research Center Program of IBS (Institute for Basic Science) in Korea (IBS-R009-D1). We also acknowledge invaluable suggestions and support from S.Y. Park, S.M. Yang, S. H. Chang, C. Kim, J.-G. Park, B.J. Yang, T.H. Kim, W. Wu and Y. Wang.

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L.W. and T.W.N. conceived the idea and designed the experiments. R.K. performed the first-principles DFT calculations. L.W. and Y.J.S. grew the samples, fabricated the Hall bar devices and performed the PFM measurements. Y.K. and M.Y.K. performed the STEM measurements. Q.F., H.Z., W.M. and Q.L. performed the MFM measurements. S.D.P., K.H.L. and H.Y. performed the numerical simulations on skyrmion stability. L.W. and T.W.N. analysed the results and wrote the manuscript. All authors participated in the discussions during manuscript preparation.

Corresponding authors

Correspondence to Lingfei Wang or Qingyou Lu or Tae Won Noh.

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Supplementary Sections 1–10, Supplementary Figures 1–26, Supplementary Notes 1–2, Supplementary References 1–29

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Wang, L., Feng, Q., Kim, Y. et al. Ferroelectrically tunable magnetic skyrmions in ultrathin oxide heterostructures. Nature Mater 17, 1087–1094 (2018). https://doi.org/10.1038/s41563-018-0204-4

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