Electrical control of spin precession in semiconductor quantum wells

Electrical tuning of coherent electron spin dynamics is demonstrated in a specially designed AlxGa1−xAs quantum well in which the Al concentration x is parabolically varied across the structure. Application of an electric bias leads to a continuous displacement of an unperturbed wave function into regions with different Al concentration. Using time-resolved optical techniques, we directly observe gate-voltage mediated tunability of electron spin precession over a View the MathML source frequency range at low temperatures and at a fixed magnetic field of View the MathML source. Such control of spin coherence persists up to room temperature. Furthermore, complete suppression of spin precession and reversal of the sign of g is demonstrated.