A tight-binding investigation of biaxial strain induced topological phase transition in GeCH$_3$

TL;DR

This paper develops a tight-binding model including spin-orbit coupling to study how biaxial strain induces a topological phase transition in GeCH$_3$, revealing potential for strain sensor applications.

Contribution

The paper introduces a tight-binding model with SOC that accurately describes GeCH$_3$ and predicts a strain-induced topological phase transition.

Findings

Topological phase transition occurs at 11.6% biaxial tensile strain.

Electronic properties are highly sensitive to strain.

Model agrees with first-principles calculations near the Fermi level.

Abstract

We propose a tight-binding (TB) model, that includes spin-orbit coupling (SOC), to describe the electronic properties of methyl-substituted germanane (GeCH$_3$). This model gives an electronic spectrum in agreement with first principle results close to the Fermi level. Using the $\mathbb{Z}_2$ formalism, we show that a topological phase transition from a normal insulator (NI) to a quantum spin Hall (QSH) phase occurs at 11.6\% biaxial tensile strain. The sensitivity of the electronic properties of this system on strain, in particular its transition to the topological insulating phase, makes it very attractive for applications in strain sensors and other microelectronic applications.