Demonstration of robust chiral edge transport in Chern insulator MnBi2Te4 devices with engineered geometric defects

TL;DR

This study experimentally confirms that chiral edge states in MnBi2Te4 Chern insulators are robust against geometric defects, using AFM nanomachining to demonstrate unaltered topological transport despite physical disruptions.

Contribution

It provides the first direct experimental evidence that engineered geometric defects do not compromise chiral edge transport in MnBi2Te4 devices.

Findings

Chiral edge states remain quantized after geometric modifications.

Edge currents bypass artificial cuts without dissipation.

AFM nanomachining effectively engineers topological device features.

Abstract

Chiral edge states in Chern insulators are theoretically predicted to propagate unidirectionally along the sample boundary with inherent robustness against local perturbations, which manifests as the immunity to impurity-induced backscattering, a key factor for the development of robust, high-performance quantum devices. However, the direct experimental verification of the robustness of chiral edge states remains scarce. Here, we experimentally validate the robustness of the chiral edge states in MnBi2Te4 devices featuring engineered geometric defects introduced via atomic force microscope (AFM) nanomachining. Specifically, under a moderate perpendicular magnetic field, the MnBi2Te4 devices exhibit the Chern insulator state, characterized by a quantized Hall plateau and simultaneously vanishing longitudinal resistance. To verify the robustness of this topological state, we modify the device geometry by cutting a slit using AFM nanomachining that severs the original edge channel. Remarkably, the quantization behavior survives this drastic modification. The robust nature of the chiral edge transport is further confirmed by two-terminal, three-terminal and non-local measurements, fully demonstrating that the edge currents can bypass the artificial cut without dissipation. Our results unambiguously demonstrate the robustness of chiral edge states against geometric disruption and establish AFM nanomachining as a promising technique for topological quantum devices engineering.