Electronic structure of buried LaNiO3 layers in (111)-oriented LaNiO3/LaMnO3 superlattices probed by soft x-ray ARPES

TL;DR

This study uses soft x-ray ARPES to investigate the electronic structure of buried LaNiO3 layers in (111)-oriented superlattices and films, revealing a 3D Fermi surface and a pseudogap that develops with reduced layer thickness.

Contribution

It provides the first detailed electronic structure measurements of buried LaNiO3 layers in (111)-oriented superlattices using soft x-ray ARPES, highlighting the evolution from metallic to insulating states.

Findings

Observation of a 3D Fermi surface in thin films

Superlattices with thicker layers are metallic, thinner layers become insulating

Presence of a 50 meV pseudogap in reduced-thickness superlattices

Abstract

Taking advantage of the large electron escape depth of soft x-ray angle resolved photoemission spectroscopy we report electronic structure measurements of (111)-oriented [LaNiO3/LaMnO3] superlattices and LaNiO3 epitaxial films. For thin films we observe a 3D Fermi surface with an electron pocket at the Brillouin zone center and hole pockets at the zone vertices. Superlattices with thick nickelate layers present a similar electronic structure. However, as the thickness of the LaNiO3 is reduced the superlattices become insulating. These heterostructures do not show a marked redistribution of spectral weight in momentum space but exhibit a pseudogap of 50 meV.