Generation of spin current by Coulomb drag
  Coulomb drag between two quantum wires is exponentially sensitive to the mismatch of their electronic densities. The application of a magnetic field can compensate this mismatch for electrons of opposite spin directions in different wires. The resulting enhanced momentum transfer leads to the conversion of the charge current in the active wire to the spin current in the passive wire. 
M. Pustilnik, E.G. Mishchenko, O.A. Starykh