We analyze the spin-orbit terms in multi-subband quasi-two-dimensional
electron systems, and how they descend from the bulk Hamiltonian of the
conduction band. Measurements of spin-orbit terms in one subband alone are
shown to give incomplete information on the spin-orbit Hamiltonian of the
system. They should be complemented by measurements of inter-subband spin-orbit
matrix elements. Tuning electron energy levels with a quantizing magnetic field
is proposed as an experimental approach to this problem.Comment: Typos noticed in the published version have been corrected and
several references added. Published in the special issue of Semiconductors in
memory of V.I. Pere