Quantized chiral edge conduction on reconfigurable domain walls of a magnetic topological insulator

The theoretical prediction [1] and experimental discovery [2] of quantum anomalous Hall effect (QAHE) in a magnetic topological insulator (TI) have opened a new playground to study the interaction between quantum Hall (QH) physics and magnetism. In quantum anomalous Hall state, the chiral edge state (CES) is predicted to appear not only at the sample edge but also at the magnetic domain wall (DW) between the up and down domains due to the discontinuous change in the Chern number. Here, we design and fabricate the magnetic domains with the tip of the magnetic force microscope (MFM) on Cr doped (Bi_xSb_1−x)₂Te₃ with stable QAHE [3], and confirmed the existence of the CES along the prescribed DWs by in-situ transport measurement. Furthermore, the proof-of-concept devices based on the reconfigurable CES are demonstrated for multiple-domain configurations [4]. The present discovery, combined with the recent spintronic developments based on the spin-momentum locking at the surface state of TI [5,6], would enable all-electrical control of the mobile DW and the CES, leading to the low power-consumption CES-based logic and memory devices in the future. [1] R. Yu et al, Science 329, 61 (2010). [2] C. Z. Chang et al, Science 340, 167(2013). [3] M. Mogi et al., Appl. Phys. Lett. 107, 182401 (2015). [4] K. Yasuda et al., arXiv:1707.09105 (2017). Accepted to Science. [5] A. R. Mellnik et al., Nature 511, 449 (2014). [6] K. Yasuda et al., Phys. Rev. Lett. 119, 137204 (2017).