Topological Current Divider in a Chern Insulator Junction

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). MnBi₂Te₄, a recently discovered van der Waals topological magnet, offers rich opportunities for Chern number engineering. Non-trivial band structures can be engineered by means of control of the magnetic state [1], while the Chern number itself can be tuned by combining the Chern insulator and quantum Hall physics [2]. In this talk, I will report a chiral edge-current divider based on Chern insulator junctions formed within the layered topological magnet MnBi₂Te₄. In a device containing a boundary between regions of different thicknesses, topological domains with different Chern numbers can coexist [2,3]. At the domain boundary, a Chern insulator junction forms, where we identify a chiral edge mode along the junction interface. I will further demonstrate how this mode can be used 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 circuit design [3].<br/>[1] Ovchinnikov, D., Huang X., Lin, Z., Fei, Z. et al. Intertwined Topological and Magnetic Orders in Atomically Thin Chern Insulator MnBi₂Te₄. Nano Lett. 21, 6, 2544–2550 (2021)<br/>[2] Cai, J., Ovchinnikov, D. et al. Electric control of a canted-antiferromagnetic Chern insulator. Nat. Commun. 13, 1668 (2022)<br/>[3] Ovchinnikov, D., Cai, J. et al. Topological current divider in a Chern insulator junction. Nat. Commun. 13, 5967 (2022)