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

Conducting boundary states in a topological insulator offer enormous potential in low energy quantum electronics. Key to efforts to develop topological electronics is the ability to precisely control the location of these states in materials. This talk will show spatial patterning of metallic edge and surface states in a single crystal of the well-known topological insulator, Sb₂Te₃. A focused ion beam, with appropriate fluence, can be used to drive a structural phase transition from a single crystal to an amorphous structure. It will be shown that this structural transition results in a concomitant topological phase transition from ℤ_2s=1 → ℤ_2s=0. The amorphous structure presents trivial, insulating bulk and surface states. Finally, experimental results will be compared with density function theory calculations, and prospects for future applications will be discussed.