Magnetic fluctuations driven insulator-to-metal transition in Ca(Ir$_{1-x}$Ru$_{x}$)O$_{3}$

TL;DR

This study reveals a direct link between magnetic fluctuation changes and the insulator-to-metal transition in Ca(Ir$_{1-x}$Ru$_{x}$)O$_{3}$, showing a shift from antiferromagnetic to ferromagnetic behavior at a critical doping level.

Contribution

It demonstrates the transition of magnetic fluctuations from antiferromagnetic to ferromagnetic at a critical doping in Ca(Ir$_{1-x}$Ru$_{x}$)O$_{3}$, establishing a clear connection with the insulator-metal transition.

Findings

Magnetic fluctuations change from antiferromagnetic to ferromagnetic at x~0.3.

The insulator-to-metal transition coincides with a change in magnetic fluctuation character.

Results suggest implications for understanding strongly correlated electron systems.

Abstract

Magnetic fluctuations in transition metal oxides are a subject of intensive research because of the key role they are expected to play in the transition from the Mott insulator to the unconventional metallic phase of these materials, and also as drivers of superconductivity. Despite much effort, a clear link between magnetic fluctuations and the insulator-to-metal transition has not yet been established. Here we report the discovery of a compelling link between magnetic fluctuations and the insulator-to-metal transition in Ca(Ir$_{1-x}$Ru$_{x}$)O$_{3}$ perovskites as a function of the doping coefficient x. We show that when the material turns from insulator to metal, at a critical value of x$\sim$ 0.3, magnetic fluctuations change their character from antiferromagnetic, a Mott insulator phase, to ferromagnetic, an itinerant electron state with Hund's orbital coupling. These results are expected to have wide-ranging implications for our understanding of the unconventional properties of strongly correlated electrons systems