Gate-tunability of electron spin precession in an InGaAs quantum well below an interdigitated ferromagnetic grating

Time-resolved Faraday rotation is used to measure the coherent electron spin precession in a GaAs/InGaAs quantum well below an interdigitated magnetized Fe grating. We show that the electron spin precession frequency can be modified by applying a gate voltage of opposite polarity to neighboring bars. A tunability of the precession frequency of 0.5~GHz/V is observed. Modulating the gate potential at a gigahertz frequency allows the electron spin precession to be controlled on a nanosecond timescale. Besides the contribution from a spatial displacement of electrons in the inhomogeneous stray field, we also observe spin precession induced by spin-orbit coupling of the moving electrons.