δ-bonding and spin-orbit coupling make SrAg4Sb2 a topological insulator

22 September 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Bonding interactions and spin-orbit coupling in the topological insulator SrAg4Sb2 are investigated using DFT with orbital projection analysis. Ag-Ag delta bonding is a key ingredient in the topological insulating state because the 4dxy + 4dx2−y2 delta antibonding band forms a band inversion with the 5s sigma bonding band. Spin-orbit coupling is required to lift d orbital degeneracies and lower the antibonding band enough to create the band inversion. These bonding effects are enabled by a longer-than-covalent Ag-Ag distance in the crystal lattice, which might be a structural characteristic of other transition metal based topological insulators. A simplified model of the topological bands is constructed to capture the essence of the topological insulating state in a way that may be engineered in other materials.

Keywords

Bonding
Transition metals
Topology
Intermetallic phases
DFT

Supplementary materials

Title
Description
Actions
Title
Supplementary figures
Description
Supplementary electronic structure figures - Brillouin zone, band structure of EuAg4Sb2, additional projected band structures and projected molecular orbitals
Actions
Title
Optimized structures
Description
Optimized structures of SrAg4Sb2 and EuAg4Sb2 in POSCAR format
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.