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

TL;DR

This paper demonstrates that reversible hydrogenation can control bulk conduction in 3D topological insulators, enabling access to surface states by tuning the Fermi level through hydrogen-induced carrier modulation.

Contribution

It introduces a reversible hydrogenation method to modulate bulk conduction in 3D topological insulators, facilitating surface state access and stability at room temperature.

Findings

Hydrogenation effectively tunes carrier density over 10^20 cm^-3.

Fermi level can be shifted into the bulk bandgap.

Surface/edge current channels become accessible through hydrogen tuning.

Abstract

Hydrogen, the smallest and most abundant element in nature, can be efficiently incorporated within a solid and drastically modify its electronic state - it has been known to induce novel magnetoelectric effects in complex perovskites and modulate insulator-to-metal transition in a correlated Mott oxide. Here we demonstrate that hydrogenation resolves an outstanding challenge in chalcogenide classes of three-dimensional (3D) topological insulators and magnets - the control of intrinsic bulk conduction that denies access to quantum surface transport. With electrons donated by a reversible binding of H+ ions to Te(Se) chalcogens, carrier densities are easily changed by over 10^20 cm^-3, allowing tuning the Fermi level into the bulk bandgap to enter surface/edge current channels. The hydrogen-tuned topological materials are stable at room temperature and tunable disregarding bulk size, opening a breadth of platforms for harnessing emergent topological states.