Crystalline Sb2Te3: Side Surfaces and Disappearance of Dirac Cones. Issue 3 (25th January 2021)

• Record Type: Journal Article
• Authors: Kolobov, Alexander V.; Fons, Paul; Saito, Yuta
• Is Part Of: Physica status solidi. Volume 15:Issue 3(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-01-25
• Subjects: Dirac cones -- phase-change memory -- Sb2Te3 -- side surfaces -- topological insulators; Solid state physics -- Periodicals; 530.4105
• DOI: 10.1002/pssr.202000418
• Languages: English
• ISSNs: 1862-6254

Abstract

Abstract : Sb2 Te3 is an end point of quasibinary GeTe–Sb2 Te3 phase‐change alloys and also a prototypical topological insulator (TI). TIs are materials that behave like insulators in their interior but whose surfaces are characterized by metallic states with linear dispersion, the so‐called Dirac cones. Such surface states are symmetry protected, robust, and are maintained even in the presence of surface defects. It has been tacitly implied that any surfaces of a TI possess this property. Herein, using ab initio simulations, it is demonstrated that cleaving Sb2 Te3 along certain side surfaces may lead to the disappearance of Dirac surface states. In particular, it is shown that the (110) surface of the typical TI Sb2 Te3 is slightly gapped, whereas the ( 1 1 ¯ 0 ) surface is metallic. The significance and potential benefits of the obtained results for practical applications in planar devices and memory cells are discussed. Abstract : Electronic structures for different side surfaces of Sb2 Te3 are reported. While van der Waals surfaces exhibit the Dirac cones, typical of topological insulators (TIs), surfaces obtained by slicing through quintuple layers can be either trivial gapped (110) or metallic ( 1 1 ¯ 0 ). The metallicity results from the creation of Te dangling bonds on the surface.