Junctions of three quantum wires for spin 1/2 electrons

TL;DR

This paper investigates how electron-electron interactions influence transport in a three-wire quantum junction with spin-1/2 electrons, revealing complex phase behavior and flux-sensitive current flow patterns.

Contribution

It introduces a detailed analysis of spin-1/2 electron effects on junction phases, highlighting new fixed points and interaction-dependent current configurations.

Findings

Identification of a chiral fixed point with asymmetric current flow

Discovery of regions with decoupled third wire due to spin effects

Comparison of spinless and spinful electron behavior in junctions

Abstract

We study the effects of electron-electron interactions on the transport properties of a junction of three quantum wires enclosing a magnetic flux. The wires are modeled as single channel spin-1/2 Tomonaga-Luttinger liquids. The system exhibits a rich phase diagram as a function of the electronic interaction strength, which includes a chiral fixed point with an asymmetric current flow highly sensitive to the sign of the flux, and another fixed point where pair tunneling dominates, similarly to the case of spinless electrons. While in the case of spinless electrons the perturbations that correspond to unequal couplings between the three wires are always irrelevant, we find that, when the electron spin is included, there are small regions in the phase diagram where a current flows only between two of the wires and the third wire is decoupled.