Mesoscopic Stoner instability in open quantum dots: suppression of Coleman-Weinberg mechanism by electron tunneling

TL;DR

This paper investigates how electron tunneling to a reservoir suppresses the Coleman-Weinberg symmetry-breaking mechanism in mesoscopic quantum dots, revealing a quantum phase transition influenced by tunneling strength.

Contribution

It demonstrates the suppression of the Coleman-Weinberg mechanism by tunneling in quantum dots and identifies a quantum phase transition driven by tunneling coupling.

Findings

Existence of a quantum phase transition at a critical tunneling coupling

Suppression of symmetry breaking due to reservoir coupling

Dependence of spin susceptibility on tunneling and temperature

Abstract

The mesoscopic Stoner instability is an intriguing manifestation of symmetry breaking in isolated metallic quantum dots, underlined by the competition between single-particle energy and Heisenberg exchange interaction. Here we study this phenomenon in the presence of tunnel coupling to a reservoir. We analyze the spin susceptibility of electrons on the quantum dot for different values of couplings and temperature. Our results indicate the existence of a quantum phase transition at a critical value of the tunneling coupling, which is determined by the Stoner-enhanced exchange interaction. This quantum phase transition is a manifestation of the suppression of the Coleman-Weinberg mechanism of symmetry breaking, induced by coupling to the reservoir.