Possible Spin Polarization in a One-Dimensional Electron Gas

TL;DR

This paper investigates conductance quantization and a 0.7 structure in a 1D electron gas, providing evidence for spin polarization at zero magnetic field likely caused by electron-electron interactions.

Contribution

It demonstrates the possible spin polarization in a 1D electron gas at zero magnetic field, linking the 0.7 structure to electron interactions and Zeeman effects.

Findings

Observation of 26 quantized conductance plateaux

Detection of a structure near 0.7(2e^2/h) at zero field

Evidence of spin polarization related to electron interactions

Abstract

In zero magnetic field, conductance measurements of clean one-dimensional (1D) constrictions defined in GaAs/AlGaAs heterostructures show twenty-six quantized ballistic plateaux, as well as a structure close to $0.7(2e^2/h)$. In an in-plane magnetic field all the 1D subbands show Zeeman splitting and in the wide channel limit the $g$-factor is $\mid g \mid = 0.4$, close to that of bulk GaAs. For the last subband spin-splitting originates from the structure at $0.7(2e^2/h)$, indicating spin polarization at $B=0$. The measured enhancement of the $g$-factor as the subbands are depopulated suggests that the ``0.7 structure'' is induced by electron-electron interactions.