Electron spin flip in III-V semiconductor quantum confined structures

Abstract

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/AlGaAs quantum ells, the spin relaxation time is found to be about several ten picoseconds at room temperature. InGaAs/InP quantum wells whose bandgap correspond to 1.5 micro 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 switching devices using this fast spin relaxation process were proposed and demonstrated. In the quantum dots, we have found that anitferromagnetic coupling between quantum dots exist at temperatures lower than 50-80K. 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 of magnitude longer than that in isolated quantum dots.