Mott Electrons in an Artificial Graphenelike Crystal of Rare-Earth Nickelate

TL;DR

This paper reports the creation of an artificial graphene-like Mott crystal using a bilayer of NdNiO3 and LaAlO3, revealing unique magnetic and orbital orderings due to geometrical engineering.

Contribution

It demonstrates the synthesis of a novel artificial crystal with unique magnetic and orbital properties not achievable in bulk or conventional heterostructures.

Findings

Presence of antiferromagnetic correlations in the artificial crystal.

Detection of an ordered orbital pattern via resonant X-ray dichroism.

Unattainable orbital arrangements in bulk or differently oriented heterostructures.

Abstract

Deterministic control over the periodic geometrical arrangement of the constituent atoms is the backbone of the material properties, that along with the interactions define the electronic and magnetic ground state. Following this notion, a bilayer of a prototypical rare-earth nickelate, NdNiO$_3$, combined with a dielectric spacer, LaAlO$_3$, has been layered along the pseudo cubic [111] direction. The resulting artificial graphene-like Mott crystal with magnetic 3$d$ electrons has antiferromagnetic correlations. In addition, a combination of resonant X-ray linear dichroism measurements and \textit{ab-initio} calculations reveal the presence of an ordered orbital pattern, which is unattainable in either bulk nickelates or nickelate based heterostructures grown along the [001] direction. These findings highlight another promising venue towards designing new quantum many-body states by virtue of geometrical engineering.