Spin properties of low-density one-dimensional wires

Abstract

We report conductance measurements of a ballistic one-dimensional (1D) wire defined in the lower two-dimensional electron gas of a GaAs/AlxGa1-xAs double quantum well. At low temperatures there is an additional structure at 0.7(2e(2)/h) in the conductance, which tends to e2/h as the electron density is decreased. We find evidence for complete spin polarization in a weakly disordered 1D wire at zero magnetic field through the observation of a conductance plateau at e2/h, which strengthens in an in-plane magnetic field and disappears with increasing electron density. In all cases studied, with increasing temperature structure occurs at 0.6(2e2/h). We suggest that the 0.7 structure is a many-body spin state excited out of, either the spin-polarized electron gas at low densities, or the spin-degenerate electron gas at high densities.