Tuning the Band Topology of GdSb by Epitaxial Strain

TL;DR

This study demonstrates how biaxial strain can continuously alter the band topology of GdSb from trivial to nontrivial, using ARPES and DFT, revealing strain-induced electronic structure changes.

Contribution

It provides the first experimental evidence of strain-tuned band topology in GdSb, combining ARPES, DFT, and a tight-binding model to explain the electronic structure evolution.

Findings

Biaxial strain tunes GdSb from trivial to nontrivial topology.

Strain reduces the gap between hole and electron bands.

Band shifts are explained by a tight-binding model considering orbital symmetry.

Abstract

Rare-earth monopnictide (RE-V) semimetal crystals subjected to hydrostatic pressure have shown interesting trends in magnetoresistance, magnetic ordering, and superconductivity, with theory predicting pressure-induced band inversion. Yet, thus far, there have been no direct experimental reports of interchanged band order in RE-Vs due to strain. This work studies the evolution of band topology in biaxially strained GdSb (001) epitaxial films using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT). We find that biaxial strain continuously tunes the electronic structure from topologically trivial to nontrivial, reducing the gap between the hole and the electron bands dispersing along the [001] direction. The conduction and valence band shifts seen in DFT and ARPES measurements are explained by a tight-binding model that accounts for the orbital symmetry of each band. Finally, we discuss the effect of biaxial strain on carrier compensation and magnetic ordering temperature.