First principles study of [111]-oriented epitaxially strained Rare-Earth Nickelate NdNiO$_3$

TL;DR

This study uses density functional theory to explore how biaxial strain affects the structural, electronic, and magnetic properties of [111]-oriented NdNiO$_3$, revealing unique phase transitions and electronic behaviors not seen in bulk or other orientations.

Contribution

It uncovers novel strain-induced structural and electronic phenomena in [111]-oriented NdNiO$_3$, expanding understanding of strain effects in rare-earth nickelates.

Findings

Strain induces unique structural phase transitions.

Tensile strain amplifies the electronic band-gap.

Charge-ordered insulating phases with non-orthorhombic tilt patterns emerge.

Abstract

Density functional theory is used to investigate the effect of biaxial strain on the structural, electronic and magnetic properties of [111]-oriented NdNiO$_3$, as a representative of the rare-earth perovskites that undergo metal-to-insulator transitions. We find that this constraint on the system induces unique structural phase transitions not previously observed under the well-studied bulk or [001]-oriented strained systems. We also report unique electronic behaviour, including amplification of the electronic band-gap with tensile strain, and insulating, charge-ordered phases with non-orthorhombic tilt patterns. To provide clarity to the trends we observe, we also investigate the coupling between the breathing mode and strain, where we observe certain strains to directly favour and disfavour the creation of the breathing mode (and thus the associated charge-ordering). The amplification of the band gap with strain is understood in terms of a cooperative coupling between the elastic constraint and octahedral breathing, which expands on the previously reported triggered mechanism mediated by octahedral tilting.