Topological current divider in a Chern insulator junction

Dmitry Ovchinnikov; Jiaqi Cai; Zhong Lin; Zaiyao Fei; Zhaoyu Liu; Yong-Tao Cui; David H Cobden; Jiun-Haw Chu; Cui-Zu Chang; Di Xiao; Jiaqiang Yan; Xiaodong Xu

doi:10.1038/s41467-022-33645-7

Topological current divider in a Chern insulator junction

Nat Commun. 2022 Oct 10;13(1):5967. doi: 10.1038/s41467-022-33645-7.

Authors

Dmitry Ovchinnikov^#¹, Jiaqi Cai^#¹, Zhong Lin¹, Zaiyao Fei¹, Zhaoyu Liu¹, Yong-Tao Cui², David H Cobden¹, Jiun-Haw Chu¹, Cui-Zu Chang³, Di Xiao^{1

4

5}, Jiaqiang Yan⁶, Xiaodong Xu^{7

8}

Affiliations

¹ Department of Physics, University of Washington, Seattle, WA, 98195, USA.
² Department of Physics and Astronomy, University of California, Riverside, CA, 92521, USA.
³ Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA.
⁴ Department of Materials Science and Engineering, University of Washington, Seattle, WA, 98195, USA.
⁵ Pacific Northwest National Laboratory, Richland, WA, USA.
⁶ Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
⁷ Department of Physics, University of Washington, Seattle, WA, 98195, USA. xuxd@uw.edu.
⁸ Department of Materials Science and Engineering, University of Washington, Seattle, WA, 98195, USA. xuxd@uw.edu.

^# Contributed equally.

Abstract

A Chern insulator is a two-dimensional material that hosts chiral edge states produced by the combination of topology with time reversal symmetry breaking. Such edge states are perfect one-dimensional conductors, which may exist not only on sample edges, but on any boundary between two materials with distinct topological invariants (or Chern numbers). Engineering of such interfaces is highly desirable due to emerging opportunities of using topological edge states for energy-efficient information transmission. Here, we report a chiral edge-current divider based on Chern insulator junctions formed within the layered topological magnet MnBi₂Te₄. We find that in a device containing a boundary between regions of different thickness, topological domains with different Chern numbers can coexist. At the domain boundary, a Chern insulator junction forms, where we identify a chiral edge mode along the junction interface. We use this to construct topological circuits in which the chiral edge current can be split, rerouted, or switched off by controlling the Chern numbers of the individual domains. Our results demonstrate MnBi₂Te₄ as an emerging platform for topological circuits design.

Grants and funding

AFOSR FA9550-21-1-0177/United States Department of Defense | United States Air Force | AFMC | Air Force Office of Scientific Research (AF Office of Scientific Research)