Topological surface currents accessed through reversible hydrogenation of the three-dimensional bulk

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Hydrogen incorporation modifies solid-state electronic and structural properties.
• Interstitial hydrogen in semiconductors is amphoteric, acting as a donor (H+) or acceptor (H-).
• Controlling bulk conduction is crucial for accessing quantum surface transport in 3D topological insulators.

Purpose of the Study:

• To address the challenge of intrinsic bulk conduction in 3D topological insulators and magnets.
• To enable access to quantum surface transport by controlling bulk conductivity.
• To develop hydrogen-based strategies for tuning topological nanostructures.

Main Methods:

• Hydrogenation of chalcogenide 3D topological insulators and magnets.
• Utilizing reversible binding of H+ ions to Te(Se) chalcogens.
• Measuring carrier density reduction and Fermi level tuning.

Main Results:

• Hydrogenation reduced carrier densities by over 10^20 cm^-3.
• Tuning of the Fermi level into the bulk bandgap was achieved.
• Carrier mobility and bandstructure remained unaltered.
• Hydrogen-tuned topological nanostructures demonstrated room temperature stability.

Conclusions:

• Hydrogenation effectively controls bulk conduction in 3D topological insulators.
• This control allows access to surface/edge current channels without compromising quantum transport properties.
• Stable, tunable topological nanostructures open new device platforms for emergent topological states.