  Spin-orbit interaction is investigated in a dual gated InAs/GaSb quantum
well. Using an electric field the quantum well can be tuned between a single
carrier regime with exclusively electrons as carriers and a two-carriers regime
where electrons and holes coexist. Spin-orbit interaction in both regimes
manifests itself as a beating in the Shubnikov-de Haas oscillations. In the
single carrier regime the linear Dresselhaus strength is characterized by
$\beta =$ 28.5 meV$\AA$ and the Rashba coefficient $\alpha$ is tuned from 75 to
53 meV$\AA$ by changing the electric field. In the two-carriers regime the spin
splitting shows a nonmonotonic behavior with gate voltage, which is consistent
with our band structure calculations.
