Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 13: Spin controlled transport I

HL 13.2: Vortrag

Dienstag, 28. März 2006, 11:15–11:30, BEY 118

Spin Relaxation Anisotropy in Semiconductor Quantum Wells — •Leonid Golub, Nikita Averkiev, Alexey Gurevich, Vadim Evtikhiev, Vladimir Kochereshko, Alexey Platonov, Alexey Shkolnik, and Yuri Dolgikh — A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia

Spin relaxation of conduction electrons is an important field of research due to rapidly developing semiconductor spintronics. The Dyakonov-Perel spin relaxation process is the dominant spin decoherence mechanism in undoped GaAs-based heterostructures. This mechanism is caused by spin splitting of electron energy spectrum which originate either from the structure inversion asymmetry (Rashba term) or the bulk inversion symmetry (Dresselhaus term). The presence of both Rashba and Dresselhaus spin-splittings results in the electron spin relaxation times anisotropy. A set of triangular and rectangular GaAs (001) quantum wells has been MBE grown on semi-insulating GaAs substrates. Circularly polarized photoluminescence (PL) spectra under circularly polarized excitation have been studied at 77K in magnetic fields up to 0.5T. The magnitude of the optical orientation signal amounts to 10% and is virtually constant within the PL contour. We observe that when the magnetic field is directed along the [110] axis the Hanle curve is about 1.6 times wider than the depolarization curve for [1-10] direction. The observed anisotropy of the Hanle effect is caused by anisotropy of the electron spin relaxation. The analysis shows that the Rashba term is about 4 times stronger than the Dresselhaus term in the studied system.