Effect of Ka-band microwave on the spin dynamics of electrons in a GaAs/Al0.35Ga0.65As heterostructure

We report experimental results of the effect of Ka-band microwave on the spin dynamics of electrons in a two-dimensional electron system (2DES) in a GaAs/Al0.35Ga0.65As heterostructure via time-resolved Kerr rotation measurements. While the microwave reduces the transverse spin lifetime of electrons in the bulk GaAs, it significantly increases that in the 2DES, from 745 to 1213 ps, when its frequency is close to the Zeeman splitting of the electrons in the magnetic field. Such a microwave-enhanced spin lifetime is ascribed to the microwave-induced electron scattering which leads to a "motional narrowing" of spins via D'yakonov-Perel' mechanism.

NSFC 10425419 National Basic Research Program of China 2007CB924900 2009CB929301 Chinese Academy of Sciences We thank M. W. Wu and X. Z. Ruan for helpful discussions. This work was supported by the NSFC under Grants No. 10425419, National Basic Research Program of China (Grant Nos. 2007CB924900 and 2009CB929301), and the Knowledge Innovation Project of Chinese Academy of Sciences.