Coupling of Magnetic Phases at Nickelate Interfaces

TL;DR

This study investigates the magnetic and metal-insulator phase coupling in artificial nickelate superlattices, revealing that magnetic phase interactions extend beyond electronic transitions, with implications for material design.

Contribution

It introduces a model system of layered SmNiO₃ and NdNiO₃ to analyze magnetic and electronic phase coupling using advanced scattering techniques.

Findings

Magnetic order evolves with temperature and superlattice periodicity.

Magnetic coupling length scale exceeds that of the electronic transition.

Landau theory explains the magnetic phase coupling behavior.

Abstract

In this work we present a model system built out of artificially layered materials, allowing us to understand the interrelation of magnetic phases with that of the metallic-insulating phase at long length-scales, and enabling new strategies for the design and control of materials in devices. The artificial model system consists of superlattices made of SmNiO$_3$ and NdNiO$_3$ layers -- two members of the fascinating rare earth nickelate family, having different metal-to-insulator and magnetic transition temperatures. By combining two complementary techniques -- resonant elastic x-ray scattering and muon spin relaxation -- we show how the magnetic order evolves, in this complex multicomponent system, as a function of temperature and superlattice periodicity. We demonstrate that the length scale of the coupling between the antiferromagnetic and paramagnetic phases is longer than that of the electronic metal-insulator phase transition -- despite being subsidiary to it. This can be explained via a Landau theory -- where the bulk magnetic energy plus a gradient cost between magnetic and non magnetic phases are considered. These results provide a clear understanding of the coupling of magnetic transitions in systems sharing identical order parameters.