From flexoelectricity to absolute deformation potentials: The case of SrTiO$_3$

TL;DR

This paper extends the concept of absolute deformation potential to nonpiezoelectric insulators, using first-principles calculations on SrTiO$_3$ to unify band-structure and electrostatic effects under strain gradients.

Contribution

It generalizes the theory of absolute deformation potentials to a broader class of materials and deformation fields, demonstrated through first-principles calculations on SrTiO$_3$.

Findings

Calculated band edge responses to dynamic and static loads in SrTiO$_3$

Unified description of strain-gradient effects on band structure and electrostatics

Implications for strain-engineered properties in crystalline insulators

Abstract

Based on recent developments in the first-principles theory of flexoelectricity, we generalize the concept of absolute deformation potential to arbitrary nonpiezoelectric insulators and deformation fields. To demonstrate our formalism, we calculate the response of the band edges of SrTiO$_3$ to both dynamic (sound waves) and static (bending) mechanical loads, respectively at the bulk level and in a slab geometry. Our results have important implications for the understanding of strain-gradient-related phenomena in crystalline insulators, formally unifying the description of band-structure and electrostatic effects.