Quasi-1D Coulomb drag between spin-polarized quantum wires

TL;DR

This study experimentally investigates Coulomb drag in quasi-1D quantum wires, confirming theoretical predictions about TLL behavior and revealing complex scattering mechanisms in spin-polarized regimes.

Contribution

First experimental verification of Coulomb drag signatures in spin-polarized quantum wires, extending TLL theory to nonreciprocal and multichannel regimes.

Findings

Observation of spin splitting in conductance and drag signals

Different power-law behaviors in spin-full and spin-polarized regimes

Correlation between subband occupation and interaction parameters

Abstract

One-dimensional (1D) quantum wires provide a versatile platform for studying strong electron-electron interactions and collective excitations under confinement. Coulomb drag between 1D systems offers a powerful probe of Tomonaga-Luttinger liquid (TLL) physics, with theoretical predictions suggesting distinct power-law in temperature dependencies between the spin-full and the spin-polarized regimes. However, experimental verification has thus far remained limited. Here, we report measurements of reciprocal and nonreciprocal Coulomb drag between vertically coupled quasi-1D quantum wires in the spin-polarized regime. Clear signatures of spin splitting are observed in both the wires conductance and the drag signal. We observed a connection between electron-hole asymmetry and negative drag, and demonstrated different power-law behaviors in spin-full and spin-polarized regimes, yielding consistent TLL interaction parameters. These results validate the theoretical predictions for backscattering induced drag in the reciprocal regime and extend them to the nonreciprocal and the multiple subband regimes. Furthermore, the nonmonotonic density dependence of the reciprocal interaction parameter correlates with the subband occupation of the drag wire, revealing the complexity of the scattering mechanisms in multichannel systems.