From Slater to Mott physics: epitaxial engineering of electronic correlations in oxide interfaces

TL;DR

This paper investigates how epitaxial strain influences electronic correlations and magnetic states in oxide interfaces, revealing pathways to control quantum phases and magnetic switching for spintronics applications.

Contribution

It introduces a comprehensive ab-initio approach to tune electronic correlations and magnetic states in Mott insulators via epitaxial engineering.

Findings

Charge transfer stabilizes high spin Fe2+ state.

Epitaxial strain controls quantum electronic phases.

Structural oxygen octahedral rotations influence electronic correlations.

Abstract

Using spin-assisted ab-initio random structure searches, we explore an exhaustive quantum phase diagram of archetypal interfaced Mott insulators, i.e. lanthanum-iron and lanthanum-titanium oxides. In particular, we report that the charge transfer induced by the interfacial electronic reconstruction stabilises a high spin ferrous Fe2+ state. We provide a pathway to control the strength of correlation in this electronic state by tuning the epitaxial strain, yielding a manifold of quantum electronic phases, i.e. Mott-Hubbard, charge transfer and Slater insulating states. Furthermore we report that the electronic correlations are closely related to the structural oxygen octahedral rotations, whose control is able to stabilise the low spin state of Fe2+ at low pressure previously observed only under the extreme high pressure conditions in the Earth's lower mantle. Thus we provide avenues for magnetic switching via THz radiations which have crucial implications for next generation of spintronics technologies.