Topological insulating behaviour in conducting property of crystalline Ge-Sb-Te

TL;DR

This paper reveals that crystalline Ge-Sb-Te materials can exhibit topological insulating properties, with conducting surface states influenced by stacking sequences and resilient to disorder, impacting their electronic behavior.

Contribution

First-principles calculations demonstrating topological insulating behavior in crystalline Ge-Sb-Te and analyzing the effects of stacking, disorder, and strain on these properties.

Findings

GST can be topological insulators depending on stacking sequence

Conducting interface states originate from Sb2Te3 layers

Interface states are resilient to atomic disorder

Abstract

We report a discovery, through first-principles calculations, that crystalline Ge-Sb-Te (GST) phase-change materials exhibit the topological insulating property. Our calculations show that the materials become topological insulator or develop conducting surface-like interface states depending on the layer stacking sequence. It is shown that the conducting interface states originate from topological insulating Sb2Te3 layers in GSTs and can be crucial to the electronic property of the compounds. These interface states are found to be quite resilient to atomic disorders but sensitive to the uniaxial strains. We presented the mechanisms that destroy the topological insulating order in GSTs and investigated the role of Ge migration that is believed to be responsible for the amorphorization of GSTs.