Electron interaction-driven insulating ground state in Bi2Se3 topological insulators in the two dimensional limit

TL;DR

This study investigates ultrathin Bi2Se3 topological insulators, revealing an electron interaction-driven insulating ground state in the two-dimensional limit through transport measurements and analysis.

Contribution

It demonstrates the crucial role of electron interactions in establishing the insulating ground state of ultrathin topological insulators, combining experimental data with theoretical insights.

Findings

Resistance increases logarithmically at low temperatures

Magnetic field enhances resistance, indicating weak antilocalization

Electron interactions are key to the insulating ground state

Abstract

We report a transport study of ultrathin Bi2Se3 topological insulators with thickness from one quintuple layer to six quintuple layers grown by molecular beam epitaxy. At low temperatures, the film resistance increases logarithmically with decreasing temperature, revealing an insulating ground state. The sharp increase of resistance with magnetic field, however, indicates the existence of weak antilocalization, which should reduce the resistance as temperature decreases. We show that these apparently contradictory behaviors can be understood by considering the electron interaction effect, which plays a crucial role in determining the electronic ground state of topological insulators in the two dimensional limit.