Chiral transport along magnetic domain walls in the quantum anomalous Hall effect

TL;DR

This paper reports the first experimental observation of chiral transport along magnetic domain walls in the quantum anomalous Hall effect, confirming theoretical predictions and demonstrating dissipationless conduction in ferromagnetic topological insulators.

Contribution

It provides the first experimental evidence of chiral transport along magnetic domain walls in the QAH system, advancing understanding of edge states in topological materials.

Findings

Observation of chiral transport along domain walls.

Evidence of mode equilibration and co-propagation.

Confirmation of theoretical predictions for domain wall conduction.

Abstract

The recent prediction, and subsequent discovery, of the quantum anomalous Hall (QAH) effect in thin films of the three-dimensional ferromagnetic topological insulator (MTI) (Cr$_y$Bi$_x$Sb$_{1-x-y}$)$_2$Te$_3$ has opened new possibilities for chiral-edge-state-based devices in zero external magnetic field. Like the $\nu=1$ quantum Hall system, the QAH system is predicted to have a single chiral edge mode circulating along the boundary of the film. Backscattering of the chiral edge mode should be suppressed, as recently verified by the observation of well-quantized Hall resistivities $\rho_{yx} = \pm h/e^2$, along with longitudinal resistivities as low as a few ohms. Dissipationless 1D conduction is also expected along magnetic domain walls. Here, we intentionally create a magnetic domain wall in a MTI and study electrical transport along the domain wall. We present the first observation of chiral transport along domain walls, in agreement with theoretical predictions. We present further evidence that two modes equilibrate and co-propagate along the length of the domain wall.