Spatial and temporal diffusive spin dynamics in the transient regime for 10-nm-wide InGaAs/InAlAs quantum wells were investigated using time-resolved optical Kerr rotation (TRKR) microscopy. The transient regime of diffusive spin dynamics is a specific regime which appears after local excitation but before the formation of a spin mode. In this regime, the spin precession frequency induced by the spin–orbit (SO) magnetic field decreases with time since the diffusive velocity decreases as the distribution of spins expands. In this study, by decreasing the spot size of the excitation pulse, we examined the spin dynamics in the transient regime. We carefully analyzed the TRKR signals using time-dependent frequency equations established by Kohda et al. [Appl. Phys. Lett. 107, 172402 (2015)]. All the TRKR signals could be well reproduced by the time-dependent frequency equations. Our analysis reveals that the spin precession frequencies arising from the SO interaction gradually decrease with time, and they allowed the extraction of the Rashba and Dresselhaus SO parameters. We revealed that SO parameters can be extracted accurately via scanning measurements in the diffusive motion of local spin excitation even in the time periods before the appearance of the spin mode.
Transient diffusive spin dynamics in intrinsic InGaAs/InAlAs multiple quantum wells
Kohei Kawaguchi, Toshiki Fukasawa, Ichirota Takazawa, Hiroki Shida, Yasuhito Saito, Daisuke Iizasa, Takahito Saito, Takahiro Kitada, Yoshihiro Ishitani, Makoto Kohda, Ken Morita; Transient diffusive spin dynamics in intrinsic InGaAs/InAlAs multiple quantum wells. Appl. Phys. Lett. 21 October 2019; 115 (17): 172406. https://doi.org/10.1063/1.5124011
Download citation file: