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Magnetic proximity and nonreciprocal current switching in a monolayer WTe2 helical edge


The integration of diverse electronic phenomena, such as magnetism and nontrivial topology, into a single system is normally studied either by seeking materials that contain both ingredients, or by layered growth of contrasting materials1,2,3,4,5,6,7,8,9. The ability to simply stack very different two-dimensional van der Waals materials in intimate contact permits a different approach10,11. Here we use this approach to couple the helical edges states in a two-dimensional topological insulator, monolayer WTe2 (refs. 12,13,14,15,16), to a two-dimensional layered antiferromagnet, CrI3 (ref. 17). We find that the edge conductance is sensitive to the magnetization state of the CrI3, and the coupling can be understood in terms of an exchange field from the nearest and next-nearest CrI3 layers that produces a gap in the helical edge. We also find that the nonlinear edge conductance depends on the magnetization of the nearest CrI3 layer relative to the current direction. At low temperatures this produces an extraordinarily large nonreciprocal current that is switched by changing the antiferromagnetic state of the CrI3.

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Fig. 1: Characteristics of a CrI3/WTe2 device with no applied field.
Fig. 2: Conductance jumps and magnetic state changes in an applied magnetic field.
Fig. 3: Nonlinear current measurements.
Fig. 4: Large nonreciprocal current controlled by the antiferromagnetic state.

Data availability

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


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The authors acknowledge L. Fidkowski and D. Xiao for insightful discussions. All the experiments and analysis were supported by National Science Foundation DMR grant nos. EAGER 1936697 and MRSEC 1719797. Materials synthesis at the University of Washington was partially supported by the Gordon and Betty Moore Foundation’s EPiQS Initiative, grant no. GBMF6759 to J.-H.C. Materials synthesis at Oak Ridge National Laboratory by M.A.M. was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

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Authors and Affiliations



D.H.C. and X.X. conceived the experiment. W.Z., Z.F., H.K.C., T.P. and B.S. fabricated the devices. W.Z. and Z.F. performed transport measurements. T.S. performed magnetic circular dichroism measurements. P.M. and J.-H.C. grew the WTe2 crystals. M.A.M. grew CrI3 crystals. D.H.C., W.Z., X.X. and Z.F. wrote the paper with comments from all authors.

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Correspondence to Xiaodong Xu or David H. Cobden.

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Supplementary Information

Supplementary Figs. 1–10, discussion and Table 1.

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Zhao, W., Fei, Z., Song, T. et al. Magnetic proximity and nonreciprocal current switching in a monolayer WTe2 helical edge. Nat. Mater. 19, 503–507 (2020).

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