Spin-incoherent transport in quantum wires

When a quantum wire is weakly confined, a conductance plateau appears at e(2)/h with decreasing carrier density in zero magnetic field accompanied by a gradual suppression of the 2e(2)/h plateau. Applying an in-plane magnetic field B(parallel to) does not alter the value of this quantization; however, the e(2)/h plateau weakens with increasing B(parallel to) up to 9 T, and then strengthens on further increasing B(parallel to), which also restores the 2e(2)/h plateau. Our results are consistent with spin-incoherent transport in a one-dimensional wire.