Top-down patterning of topological surface and edge states using a focused ion beam.

Bake, Abdulhakim; Zhang, Qi; Ho, Cong Son; Causer, Grace L; Zhao, Weiyao; Yue, Zengji; Nguyen, Alexander; Akhgar, Golrokh et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

The conducting boundary states of topological insulators appear at an interface where the characteristic invariant ℤ2 switches from 1 to 0. These states offer prospects for quantum electronics; however, a method is needed to spatially-control ℤ2 to pattern conducting channels. It is shown that modifying Sb2Te3 single-crystal surfaces with an ion beam switches the topological insulator into an amorphous state exhibiting negligible bulk and surface conductivity. This is attributed to a transition from ℤ2 = 1 → ℤ2 = 0 at a threshold disorder strength. This observation is supported by density functional theory and model Hamiltonian calculations. Here we show that this ion-beam treatment allows for inverse lithography to pattern arrays of topological surfaces, edges and corners which are the building blocks of topological electronics.