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

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Science  08 Dec 2017:
Vol. 358, Issue 6368, pp. 1311-1314
DOI: 10.1126/science.aan5991

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A magnetic tip reconfigures edge states

Topological phases of matter are characterized by invariants such as Chern numbers, which determine their global properties. On the boundary of two domains with different Chern numbers, chiral edge states are expected to form. Yasuda et al. engineered such states in samples of a quantum anomalous Hall material by creating magnetic domains using the tip of a magnetic force microscope. The existence of chiral edge states along the domain walls was confirmed with electrical transport measurements. The ability to reconfigure and manipulate these states may improve spintronics.

Science, this issue p. 1311

Abstract

Electronic ordering in magnetic and dielectric materials forms domains with different signs of order parameters. The control of configuration and motion of the domain walls (DWs) enables nonvolatile responses against minute external fields. Here, we realize chiral edge states (CESs) on the magnetic DWs of a magnetic topological insulator. We design and fabricate the magnetic domains in the quantum anomalous Hall state with the tip of a magnetic force microscope and prove the existence of the chiral one-dimensional edge conduction along the prescribed DWs through transport measurements. The proof-of-concept devices based on reconfigurable CESs and Landauer-Büttiker formalism are realized for multiple-domain configurations with well-defined DW channels. Our results may lead to the realization of low-power-consumption spintronic devices.

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