Mesoscopic Stoner instability in metallic nanoparticles revealed by shot noise

TL;DR

This paper investigates how shot noise reveals the mesoscopic Stoner instability in metallic nanoparticles, showing oscillations in the Fano factor linked to spin excitations, and proposes shot noise as a diagnostic tool.

Contribution

It demonstrates that shot noise oscillations can serve as a probe for the mesoscopic Stoner instability in metallic nanoparticles, providing new insights into spin-related transport phenomena.

Findings

Fano factor exhibits oscillations between super- and sub-Poissonian values with bias voltage.

Transport channels open successively with increasing bias, associated with nanoparticle spin excitations.

Shot noise can be used as an effective tool to detect the mesoscopic Stoner instability.

Abstract

We study sequential tunneling through a metallic nanoparticle close to the Stoner instability coupled to parallely magnetized electrodes. Increasing the bias voltage successively opens transport channels associated with excitations of the nanoparticle's total spin. For the current this leads just to a steplike increase. The Fano factor, in contrast, shows oscillations between large super-Poissonian and sub-Poissonian values as a function of bias voltage. We explain the enhanced Fano factor in terms of generalized random-telegraph noise and propose the shot noise as a convenient tool to probe the mesoscopic Stoner instability.