  We study the spin polarization induced by a current flow in clean two
dimensional electron gases with Rashba spin-orbit coupling. This geometric
effect originates from special properties of the electron's scattering at the
edges of the sample. In wide samples, the spin polarization has it largest
value at low energies (close to the bottom of the band) and goes to zero at
higher energies. In this case, the spin polarization is dominated by the
presence of evanescent modes which have an explicit spin component outside the
plane. In quantum wires, on the other hand, the spin polarization is dominated
by interference effects induced by multiple scattering at the edges. Here, the
spin polarization is quite sensitive to the value of the Fermi energy,
especially close to the point where a new channel opens up. We analyzed
different geometries and found that the spin polarization can be strongly
enhanced.
