Integer quantum Hall effect and topological phase transitions in silicene

TL;DR

This paper numerically studies how disorder affects the quantum Hall effect and topological phase transitions in silicene, revealing the fragility of certain Hall plateaus and the conditions for phase changes between topological and band insulators.

Contribution

It provides new insights into the disorder-induced destruction of Hall plateaus and the electric field-driven topological phase transitions in silicene.

Findings

Unconventional QHE near band center with specific plateaus

Disorder destroys higher Hall plateaus first, with the a00a0 plateau being most sensitive

Electric field and spin-orbit interaction induce topological to band insulator transitions

Abstract

We numerically investigate the effects of disorder on the quantum Hall effect (QHE) and the quantum phase transitions in silicene based on a lattice model. It is shown that for a clean sample, silicene exhibits an unconventional QHE near the band center, with plateaus developing at $\nu=0,\pm2,\pm6,\ldots,$ and a conventional QHE near the band edges. In the presence of disorder, the Hall plateaus can be destroyed through the float-up of extended levels toward the band center, in which higher plateaus disappear first. However, the center $\nu=0$ Hall plateau is more sensitive to disorder and disappears at a relatively weak disorder strength. Moreover, the combination of an electric field and the intrinsic spin-orbit interaction (SOI) can lead to quantum phase transitions from a topological insulator to a band insulator at the charge neutrality point (CNP), accompanied by additional quantum Hall conductivity plateaus.