Signatures of spin-charge separation in double--quantum-wire tunneling

TL;DR

This paper provides experimental evidence for spin-charge separation in coupled quantum wires by analyzing tunneling spectra and conductance oscillations, revealing multiple excitation velocities and interference effects.

Contribution

It demonstrates spin-charge separation in double quantum wires through tunneling spectroscopy and interference pattern analysis, a novel experimental observation.

Findings

Detection of multiple excitation velocities

Interference pattern due to boundary effects

Modulation of conductance oscillations explained by spin-charge separation

Abstract

We present evidence for spin-charge separation in the tunneling spectrum of a system consisting of two quantum wires connected by a long narrow tunnel junction at the edge of a GaAs/AlGaAs bilayer heterostructure. Multiple excitation velocities are detected in the system by tracing out electron spectral peaks in the conductance dependence on the applied voltage, governing the energy of tunneled electrons, and the magnetic field, governing the momentum shift along the wires. The boundaries of the wires are important and lead to a characteristic interference pattern in measurements on short junctions. We show that the experimentally observed modulation of the conductance oscillation amplitude as a function of the voltage bias can also be accounted for by spin-charge separation of the elementary excitations in the interacting wires.