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

Area of Science:

• Condensed matter physics
• Materials science
• Quantum electronics

Background:

• Topological insulators possess conducting boundary states crucial for quantum electronics.
• Spatially controlling the topological invariant (ℤ₂ ) is essential for patterning these conducting channels.
• Current methods lack precise spatial control over the topological state.

Purpose of the Study:

• To develop a method for spatially controlling the topological invariant (ℤ₂ ) in topological insulators.
• To enable the patterning of conducting channels for topological electronics.

Main Methods:

• Utilizing ion beam irradiation on antimony telluride (Sb₂Te₃) single-crystal surfaces.
• Employing density functional theory and model Hamiltonian calculations for theoretical support.

Main Results:

• Ion beam treatment transforms the topological insulator into an amorphous state.
• This transition effectively switches the topological invariant from ℤ₂ = 1 to ℤ₂ = 0.
• Negligible bulk and surface conductivity were observed in the amorphous state, indicating a robust topological phase transition.
• Demonstrated inverse lithography to pattern topological surfaces, edges, and corners.

Conclusions:

• Ion beam modification provides a viable route for inverse lithography of topological materials.
• This technique allows for the creation of patterned topological states, essential for building blocks of topological electronics.
• The findings pave the way for novel quantum electronic devices with precisely engineered topological properties.