Influence of Magnetic Moment Formation on the Conductance of Coupled Quantum Wires

TL;DR

This paper models how local magnetic moments in coupled quantum wires influence their conductance, explaining experimental resonant peaks and conductance features through a theoretical inter-wire interaction framework.

Contribution

It introduces a theoretical model linking local magnetic moment formation to conductance resonances in coupled quantum wires, aligning with experimental observations.

Findings

Resonant conductance peaks are linked to local moment formation.

Additional conductance structures appear near 0.75 and 0.25 times 2e^2/h.

The model explains experimental conductance features in coupled quantum wires.

Abstract

In this report, we develop a model for the resonant interaction between a pair of coupled quantum wires, under conditions where self-consistent effects lead to the formation of a local magnetic moment in one of the wires. Our analysis is motivated by the experimental results of Morimoto et al. [Appl. Phys. Lett. \bf{82}, 3952 (2003)], who showed that the conductance of one of the quantum wires exhibits a resonant peak at low temperatures, whenever the other wire is swept into the regime where local-moment formation is expected. In order to account for these observations, we develop a theoretical model for the inter-wire interaction that calculated the transmission properties of one (the fixed) wire when the device potential is modified by the presence of an extra scattering term, arising from the presence of the local moment in the swept wire. To determine the transmission coefficients in this system, we derive equations describing the dynamics of electrons in the swept and fixed wires of the coupled-wire geometry. Our analysis clearly shows that the observation of a resonant peak in the conductance of the fixed wire is correlated to the appearance of additional structure (near $0.75\cdot$ or $0.25\cdot 2e^2/h$) in the conductance of the swept wire, in agreement with the experimental results of Morimoto et al.