Two-dimensional imaging of the spin-orbit effective magnetic field

We report on spatially resolved measurements of the spin-orbit effective magnetic field in a GaAs/InGaAs quantum well. Biased gate electrodes lead to an electric-field distribution in which the quantum-well electrons move according to the local orientation and magnitude of the electric field. This motion induces Rashba and Dresselhaus effective magnetic fields. The projection of the sum of these fields onto an external magnetic field is monitored locally by measuring the electron spin-precession frequency using time-resolved Faraday rotation. A comparison with simulations shows good agreement with the experimental data.