Ultrafast spin evolution in high-mobility 2DEGs

We describe optical measurements of electron spin dynamics in a high-mobility n-doped GaAs/AlGaAs quantum well which test the customary assumptions of the Dʹyakonov, Perel’ and Kachorovskii mechanism of electron spin relaxation. At View the MathML source, spin evolution is oscillatory indicating breakdown of collision-dominated relaxation. At higher temperatures spin evolution is exponential but extracted scattering times deviate strongly from transport momentum relaxation times. This discrepancy can be ascribed to electron–electron scattering previously overlooked as a contributor to spin relaxation.