Doping induced site-selective Mott insulating phase in LaFeO$_3$

TL;DR

This paper reports the discovery of a site-selective Mott insulating phase in LaFeO$_3$ induced by Mo doping, where metallic and localized electrons coexist, leading to a rare combination of antiferromagnetism, metallicity, and charge disproportionation.

Contribution

It demonstrates a novel doping-induced phase in LaFeO$_3$ with coexisting metallicity, antiferromagnetism, and charge disproportionation, expanding understanding of correlated oxides.

Findings

Mo doping induces a site-selective Mott insulator state.

The state exhibits coexistence of metallicity and localized carriers.

Charge disproportionation occurs without destroying antiferromagnetic order.

Abstract

Tailoring transport properties of strongly correlated electron systems in a controlled fashion counts among the dreams of materials scientists. In copper oxides, varying the carrier concentration is a tool to obtain high-temperature superconducting phases. In manganites, doping results in exotic physics such as insulator-metal transitions (IMT), colossal magnetoresistance (CMR), orbital- or charge-ordered (CO) or charge-disproportionate (CD) states. In most oxides, antiferromagnetic order and charge-disproportionation are asssociated with insulating behavior. Here we report the realization of a unique physical state that can be induced by Mo doping in LaFeO$_3$: the resulting metallic state is a site-selective Mott insulator where itinerant electrons evolving in low-energy Mo states coexist with localized carriers on the Fe sites. In addition, a local breathing-type lattice distortion induces charge disproportionation on the latter, without destroying the antiferromagnetic order. A state, combining antiferromangetism, metallicity and CD phenomena is rather rare in oxides and may be of utmost significance for future antiferromagnetic memory devices.