Electrical measurement of pure spin currents in a two dimensional electron gas

We present an electrical measurement of pure spin currents in a $AlGaAs/GaAs$ two dimensional electron gas. Spin polarized electrons are injected into the centre of a $90\mu$m long channel through a quantum point contact (QPC) in a large in-plane magnetic field. The charge current flows to one end of the channel. A pure spin current flows to the opposite end, driven by a chemical potential difference between the two spin populations. This difference is recorded using spin polarized QPCs along the channel in regions free of charge current.