Quantum criticality near the Stoner transition in a two-dot with spin-orbit coupling

TL;DR

This paper investigates quantum critical behavior near the Stoner transition in a two-dot system with spin-orbit coupling, using large-N approximation to analyze quasiparticle decay rate crossover.

Contribution

It introduces a theoretical framework to describe quantum criticality in a coupled two-dot system with spin-orbit effects, focusing on the crossover of quasiparticle decay rates.

Findings

Derived a scaling function for quasiparticle decay rate crossover.

Identified quantum critical regime near the Stoner transition.

Applied large-N approximation for reliable calculations in strongly fluctuating regimes.

Abstract

We study a system of two tunnel-coupled quantum dots, with the first dot containing interacting electrons (described by the Universal Hamiltonian) not subject to spin-orbit coupling, whereas the second contains non-interacting electrons subject to spin-orbit coupling. We focus on describing the behavior of the system near the Stoner transition. Close to the critical point quantum fluctuations become important and the system enters a quantum critical regime. The large-$N$ approximation allows us to calculate physical quantitites reliably even in this strongly fluctuating regime. In particular, we find a scaling function to describe the crossover of the quasiparticle decay rate between the renormalized Fermi liquid regime and the quantum critical regime.