Asymmetric orbital-lattice interactions in ultra-thin correlated oxide films

TL;DR

This study reveals how asymmetric orbital-lattice interactions in ultra-thin LaNiO3 films, driven by strain, induce charge ordering and orbital modifications, offering new avenues for designing correlated oxide materials.

Contribution

It demonstrates strain-induced asymmetric orbital responses and emergent charge order in ultra-thin LaNiO3 films, a phenomenon not observed in bulk materials.

Findings

Strain controls octahedral distortions and charge order.

Orbital responses are asymmetric and strain-dependent.

New pathway for orbital engineering in correlated oxides.

Abstract

Using resonant X-ray spectroscopies combined with density functional calculations, we find an asymmetric bi-axial strain-induced $d$-orbital response in ultra-thin films of the correlated metal LaNiO$_3$ which are not accessible in the bulk. The sign of the misfit strain governs the stability of an octahedral "breathing" distortion, which, in turn, produces an emergent charge-ordered ground state with an altered ligand-hole density and bond covalency. Control of this new mechanism opens a pathway to rational orbital engineering, providing a platform for artificially designed Mott materials.