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 ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ devices by introducing engineered geometric defects via atomic force microscopy (AFM) nanomachining. Specifically, under a moderate perpendicular magnetic field, the ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ 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 creating a structural cut that reaches the substrate using AFM nanomachining. 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 nonlocal measurements, demonstrating that the edge currents can survive the engineered cut. Our results provide strong evidence for the robustness of chiral edge states against geometric disruption and establish AFM nanomachining as a promising technique for topological quantum devices engineering.

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• Ballistic transport
• Topological phases of matter
• Transport phenomena
• Chern insulators
• Topological materials
• Cryogenics
• Hall bar
• Liquid helium cooling
• Resistivity measurements