Prediction of topological insulators consisting of Thallium with group V elements

• Main Authors: Shu-ming Lai, 賴書明
• Other Authors: Feng-Chuan Chuang
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/8zk96s

碩士 === 國立中山大學 === 物理學系研究所 === 103 === We used first-principles electronic structure calculations to predict topological properties in binary compositions of Thallium (Tl) and group V elements in bulks and thin films. Determined by the calculated the topological invariants (Z2), we identified bulk TlBi is a weak topological insulator (TI) and a semimetal. Furthermore, bulk TlP and TlAs are metals and become topological insulator and then semimetal under external strain. As for two-dimensional thin films, we found nontrivial TI phase in two bilayers of hydrogenated TlAs and TlSb, which can withstand a wide range of strain. Additionally, TlN and TlBi could still be driven to nontrivial phase at some strain values. We note energy gaps of all the two-dimensional thin files generally less than 80 meV. Their application at room temperature is pending further studies.