TUNABLE SPIN-SPLITTING AND SPIN-RESOLVED BALLISTIC TRANSPORT IN GAAS ALGAAS 2-DIMENSIONAL HOLES/

We report quantitative experimental and theoretical results revealing the tunability of spin splitting in high-mobility two-dimensional GaAs hole systems, confined to either a square or a triangular quantum wel l, via the application of a surface-gate bias. The spin splitting depe nds on both the hole density and the symmetry of the confinement poten tial and is largest for the highest densities in asymmetric potentials . In the triangular well, when the spin splitting is sufficiently larg e, our measured commensurability oscillations, induced by a one-dimens ional periodic potential, exhibit two frequencies providing clear evid ence for spin-resolved ballistic transport.