Electron spin flip in 111-V semiconductor cuantum confined structures

We report on the fast spin flip process in quantum wells and quantum dots. The utilization of spin degree of freedom will open the door to novel functional devices. In the GaAs/A1GaAs quantum wells, the spin relaxation time is found to be about several ten picoseconds at room temperature. JnGaAs/InP quantum wells whose bandgap correspond to 1.5 micron meters have the fast spin relaxation of several picoseconds. Regarding to GaAs/AlGaAs multiple-quantum wells, we observed that Dyakonov-Perel process governs the spin relaxation at room temperature. All optical switiching devices using this fast spin relaxation process were proposed and demonstrated. In the quantum dots, we have found that antiferromagnetic coupling between quantum dots exist at temperatures lower than 50-80 K. The electron spin flips within 70-200 Ps after the carrier generation. The spin relaxation time under the antiferromagnetic order is extended to 10-12 ns, an order ofmagnitude longer than that in isolated quantum dots.