Latent Instabilities in Metallic LaNiO3 Films by Strain Control of Fermi-Surface Topology

TL;DR

This study explores how strain alters the electronic structure and Fermi-surface topology in LaNiO3 films, revealing potential instabilities and phase transitions driven by strain-induced modifications.

Contribution

It provides detailed experimental and theoretical insights into strain-induced Fermi-surface topology changes and emergent instabilities in LaNiO3 films, a strongly correlated oxide.

Findings

Fermi-surface topology changes from three- to quasi-two-dimensional with tensile strain.

A new Fermi-surface superstructure with Q2 modulation appears under tensile strain.

Presence of instabilities such as charge disproportionation and spin-density-wave fluctuations.

Abstract

Strain control is one of the most promising avenues to search for new emergent phenomena in transition-metal-oxide films. Here, we investigate the strain-induced changes of electronic structures in strongly correlated LaNiO3 (LNO) films, using angle-resolved photoemission spectroscopy and the dynamical mean-field theory. The strongly renormalized eg-orbital bands are systematically rearranged by misfit strain to change its fermiology. As tensile strain increases, the hole pocket centered at the A point elongates along the kz-axis and seems to become open, thus changing Fermi-surface (FS) topology from three- to quasi-two-dimensional. Concomitantly, the FS shape becomes flattened to enhance FS nesting. A FS superstructure with Q1 = (1/2,1/2,1/2) appears in all LNO films, while a tensile-strained LNO film has an additional Q2 = (1/4,1/4,1/4) modulation, indicating that some instabilities are present in metallic LNO films. Charge disproportionation and spin-density-wave fluctuations observed in other nickelates might be their most probable origins.