Effect of the heterointerface on the spin splitting in modulation doped InxGa1−xAs/InP quantum wells for B→0

Spin splitting of conduction band electrons in ${\mathrm{In}}_{\text{0.53}}{\mathrm{Ga}}_{\text{0.47}}{\mathrm{As/In}}_{\text{0.77}}{\mathrm{Ga}}_{\text{0.23}}\mathrm{As/InP}$ heterostructures due to spin-orbit coupling is studied by performing Shubnikov–de Haas measurements on nongated and gated Hall bars. From an analysis of the beating pattern in the Shubnikov–de Haas oscillations, the spin-orbit coupling constant is determined. For a symmetric sample no beating pattern and thus no spin splitting is observed. This demonstrates that the $k^3$ contribution to the spin-orbit coupling constant can be neglected. By applying an envelope function theory it is shown that the major contribution to the Rashba spin-orbit coupling originates from the band offset at the interface of the quantum well. Using gated Hall bar structures it is possible to alter the spin-orbit coupling by application of an appropriate gate voltage. A more negative gate voltage leads to a more pronounced asymmetry of the quantum well, which gives rise to a stronger spin-orbit coupling.