Spin-dependent transport in a quasiballistic wire

We describe the transport properties of a 5 mum long one-dimensional (1D) quantum wire. In an in-plane magnetic field B-parallel to, we observe spin-splitting of 1D conductance steps. Our results provide evidence that deviation from conductance quantisation is very small for electrons with spin parallel and is about 1/3 for electrons with spin anti-parallel. Moreover, in a high B-parallel to, a spin-polarised 1D channel shows a plateau-like structure close to 0.3 x 2e(2)/h which strengthens with increasing temperature. It is suggested that these results arise from the combination of disorder and the electron-electron interactions in the 1D electron gas.