Electron-spin dephasing in GaAs/Al0.34Ga0.66As quantum wells with a gate-controlled electron density

The dynamics of electron-spin coherence in GaAs/Al0.34Ga0.66As quantum wells has been studied experimentally by a pump-probe Kerr rotation technique. The electron-spin dephasing time was measured to be 10 ns for a 17-nm quantum well containing about 10(10) cm(-2) background electrons at a temperature of 1.8 K. Decrease of the electron density causes a decrease of dephasing time by an order of magnitude. Local fluctuations of the effective magnetic field of the nuclear spins was established as a dominating spin dephasing mechanism for localized electrons in the quantum wells.