Itinerant Ferromagnetism in the electronic localization limit

TL;DR

This study investigates ultrathin ferromagnetic metal films, revealing that itinerant ferromagnetism is suppressed by electronic disorder in the strong localization regime, with ferromagnetism only present below a critical resistance.

Contribution

It demonstrates the suppression of itinerant ferromagnetism in ultrathin films due to electronic localization effects, highlighting the role of disorder in magnetic properties.

Findings

Ferromagnetism appears only below a critical resistance $R_{C}$.

Films with resistance above $R_{C}$ show no ferromagnetism.

Suppression of ferromagnetism linked to electronic disorder in the localization regime.

Abstract

We present Hall effect, $R_{xy}(H)$, and magnetoresistance, $R_{xx}(H)$, measurements of ultrathin films of Ni, Co and Fe with thicknesses varying between 0.2-8 nm and resistances between 1 M$\Omega$ - 100 $\Omega.$ Both measurements show that films having resistance above a critical value, $R_{C}$, (thickness below a critical value, $d_{C}$) show no signs for ferromagnetism. Ferromagnetism appears only for films with $R<R_{C}$, where $R_{C}$ is material dependent. We raise the possibility that the reason for the absence of spontaneous magnetization is suppression of itinerant ferromagnetism by electronic disorder in the strong localization regime.