  It is shown that the spin orientation of free electrons occurs in
low-symmetry semiconductor structures if only the electron gas is driven out of
thermal equilibrium with the crystal lattice. The proposed mechanism of such a
thermal orientation of electron spins is based on spin dependence of the
electron-phonon interaction which tends to restore equilibrium. The microscopic
theory of the effect is developed here for asymmetric (110)-grown quantum wells
where the electron gas heating leads to the spin orientation along the [1-10]
axis in the quantum well plane.
