Disentangled cooperative orderings in artificial rare-earth nickelates

TL;DR

This study introduces superlattices combining Mott insulators and correlated metals to selectively control and disentangle coupled phase transitions in rare-earth nickelates, revealing the site selective Mott transition as the key driver.

Contribution

The paper demonstrates a novel heterostructure design that decouples charge, magnetic, and metal-insulator transitions in $RE$NiO$_3$, clarifying the transition mechanisms.

Findings

Suppression of charge order transition in tailored superlattices

Preservation of metal-insulator and magnetic transitions

Identification of site selective Mott transition as the driving mechanism

Abstract

Coupled transitions between distinct ordered phases are important aspects behind the rich phase complexity of correlated oxides that hinders our understanding of the underlying phenomena. For this reason, fundamental control over complex transitions has become a leading motivation of the designer approach to materials. We have devised a series of new superlattices by combining a Mott insulator and a correlated metal to form ultra-short period superlattices, which allow one to disentangle the simultaneous orderings in $RE$NiO$_3$. Tailoring an incommensurate heterostructure period relative to the bulk charge ordering pattern suppresses the charge order transition while preserving metal-insulator and antiferromagnetic transitions. Such selective decoupling of the entangled phases resolves the long-standing puzzle about the driving force behind the metal-insulator transition and points to the site selective Mott transition as the operative mechanism. This designer approach emphasizes the potential of heterointerfaces for selective control of simultaneous transitions in complex materials with entwined broken symmetries.