Spin dynamics in the second subband of a quasitwo-dimensional system studied in a single-barrier heterostructure by time-resolved Kerr rotationF. Zhang, H. Z. Zheng, Y. Ji, J. Liu and G. R. Li
State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences - P.O. Box 912, Beijing 100083, China
received 27 March 2008; accepted in final form 25 June 2008; published August 2008
published online 6 August 2008
Spin dynamics in the first and second subbands have been examined simultaneously by time resolved Kerr rotation in a single-barrier heterostructure of a 500 nm thick GaAs absorption layer. By scanning the wavelengths of the probe and pump beams towards the short wavelength in the zero magnetic field, the spin coherent time T21* in the subband E1 decreases in accordance with the D'yakonov-Perel' (DP) spin decoherence mechanism. Meanwhile, the spin coherence time T22* in the subband E2 remains very low at wavelengths longer than 810 nm, and then is dramatically enhanced afterwards. At 803 nm, becomes ten times longer than . A new feature has been discovered at the wavelength of 811 nm under the bias of (807 nm under the bias of ) that the spin coherence times ( T21* and T22* ) and the effective g* factors ( |g*(E1)| and |g*(E2)|) all display a sudden change, presumably due to the "resonant" spin exchange coupling between two spin opposite bands.
72.25.Fe - Optical creation of spin polarized carriers.
72.25.Dc - Spin polarized transport in semiconductors.
78.47.-p - Spectroscopy of solid state dynamics.
© EPLA 2008