Superlattice modification of the valence-band spin splitting inInxGa1−xAs/GaAs superlattices up to 45 T

We report interband magneto-optics on a series of ${\mathrm{In}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs superlattices in pulsed magnetic fields up to 45 T. The experiments demonstrate 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 experimental data and show that the heavy-hole spin splitting passes through zero at low fields for a weakly coupled superlattice, but that this moves up to ∼40 T when strong interwell coupling occurs.