Nonlinear transport in a single-mode one-dimensional electron gas

Focusing on the last spin-degenerate one-dimensional subband, conductance measurements of split-gate devices were carried out in the linear and nonlinear regimes. In the linear regime, we observed a structure at 0.7(2e 2/h) in addition to the quantized plateaux. In a strong in-plane magnetic field B this 0.7 structure evolves into the spin-split plateau at e 2/h, suggesting a possible spin polarization for the last subband at B = 0. The 0.7 structure and the e 2/h plateau show similar source—ain bias dependence, suggesting that the 0.7 structure has origin in the lower spin subband.