SUPERLATTICE MODIFICATION OF THE VALENCE-BAND SPIN SPLITTING IN INXGA1-XAS GAAS SUPERLATTICES UP TO 45-T/

We report interband magneto-optics on a series of InxGa1-xAs/GaAs supe rlattices in pulsed magnetic fields up to 45 T. The experiments demons trate that the heavy-hole spin splitting is strongly dependent on the degree of interwell coupling in the valence band. Calculations of the Landau levels in these structures give very good agreement with the ex perimental data and show that the heavy-hole spin splitting passes thr ough zero at low fields for a weakly coupled superlattice, but that th is moves up to approximately 40 T when strong interwell coupling occur s.