Interplay of orbital effects and nanoscale strain in topological crystalline insulators

TL;DR

This paper investigates how nanoscale strain influences the electronic band structure of topological crystalline insulators, revealing orbital-dependent effects that could impact future material design.

Contribution

It demonstrates for the first time that strain effects on band structure are significantly affected by the orbital nature of the electronic states in topological crystalline insulators.

Findings

Strain in one direction affects band structure in the perpendicular direction.

Orbital nature of bands causes non-trivial strain effects.

Microscopic models must include orbital considerations for accurate predictions.

Abstract

Orbital degrees of freedom can have pronounced effects on the fundamental properties of electrons in solids. In addition to influencing bandwidths, gaps, correlation strength and dispersion, orbital effects have also been implicated in generating novel electronic and structural phases, such as Jahn-Teller effect and colossal magnetoresistance. In this work, we show for the first time how the orbital nature of bands can result in non-trivial effects of strain on the band structure. We use scanning tunneling microscopy and quasiparticle interference imaging to study the effects of strain on the electronic structure of a heteroepitaxial thin film of a topological crystalline insulator, SnTe. We find a surprising effect where strain applied in one direction affects the band structure in the perpendicular direction. Our theoretical calculations indicate that this effect directly arises from the orbital nature of the conduction and valance bands. Our results imply that a microscopic model capturing strain effects on the band structure must include a consideration of the orbital nature of the bands.