Quantum confinement of Mott electrons in ultrathin LaNiO3/LaAlO3 superlattice

TL;DR

This study explores how quantum confinement in ultrathin LaNiO3/LaAlO3 superlattices induces a Mott transition from metallic to insulating behavior, revealing charge ordering tendencies and electronic structure modifications.

Contribution

It demonstrates the emergence of a Mott insulator state in ultrathin LaNiO3 layers due to quantum confinement effects, supported by experimental and ab initio calculations.

Findings

Observation of a Mott transition near the quantum confinement limit.

Suppression of apical ligand hole density affecting electronic structure.

Support for a Mott insulator ground state from dynamical-mean-field calculations.

Abstract

We investigate the electronic reconstruction in (LaNiO$_{3}$)$_n$/(LaAlO$_{3}$)$_3$ (n=3, 5 and 10) superlattices due to the quantum confinement (QC) by d.c. transport and resonant soft x-ray absorption spectroscopy. In proximity to the QC limit, a Mott-type transition from an itinerant electron behavior to a localized state is observed. The system exhibits tendency towards charge-order during the transition. ab initio cluster calculations are in good agreement with the absorption spectra, indicating that the apical ligand hole density is highly suppressed resulting in a strong modification of the electronic structure. At the dimensional crossover cellular dynamical-mean-field calculations support the emergence of a Mott insulator ground state in the heterostructured ultra-thin slab of LaNiO$_{3}$.