  A dual-gate InSb nanosheet field-effect device is realized and is used to
investigate the physical origin and the controllability of the spin-orbit
interaction in a narrow bandgap semiconductor InSb nanosheet. We demonstrate
that by applying a voltage over the dual gate, efficiently tuning of the
spin-orbit interaction in the InSb nanosheet can be achieved. We also find the
presence of an intrinsic spin-orbit interaction in the InSb nanosheet at zero
dual-gate voltage and identify its physical origin as a build-in asymmetry in
the device layer structure. Having a strong and controllable spin-orbit
interaction in an InSb nanosheet could simplify the design and realization of
spintronic deceives, spin-based quantum devices and topological quantum
devices.
