HOLE STATES IN GAAS ALAS HETEROSTRUCTURES AND THE LIMITATIONS OF THE LUTTINGER MODEL/

We present microscopic results for hole scattering at a [001] GaAs-AlA s single interface, with k(parallel-to) = 0, which show strong bulk li ght hole - heavy hole mixing. The hole scattering process is found to be due to the differences in the cell periodic wavefunctions of the ma terials of the interface, invalidating the fundamental assumption of t he effective mass theory of hole states in heterostructures. We show t hat the mixing of light- and heavy-hole states is much larger than tha t obtained from a phenomenological model based on the Luttinger Hamilt onian. The time reversal symmetry aspects of bulk Bloch spinor states, in the presence of the spin-orbit interaction, are found to play an i mportant role in determining the magnitude of the scattering amplitude s of the various bulk states. In the light of these calculations, we q uestion the validity of the effective mass theory/Luttinger Hamiltonia n approach, usually employed to describe heterostructure hole states.