1305.3361 (L. Wang et al.)
L. Wang, M. W. Wu
Intrinsic electron spin relaxation due to the D'yakonov-Perel' mechanism is studied in monolayer MoS$_2$ with the electron-impurity, electron-electron Coulomb, (both the intra- and inter-valley) electron-phonon scatterings explicitly included. We find that only the intervalley electron-phonon scattering contributes to the intrinsic in-plane spin relaxation whereas the contributions of other scatterings are absent. This originates from the unique momentum-independent intrinsic spin-orbit coupling, which only serves as a Zeeman-like term with opposite effective magnetic fields perpendicular to the monolayer MoS$_2$ plane in the two valleys. The Zeeman-like term opens an intervalley spin relaxation channel together with the intervalley electron-phonon scattering. The intervalley electron-phonon scattering is always in the weak scattering limit, which makes the in-plane spin relaxation time proportional to the intervalley momentum scattering time. This leads to a rapid decrease of the in-plane spin relaxation time with increasing temperature due to the enhancement of the intervalley scattering. In addition, we predict a peak in the electron-density dependence of the in-plane spin relaxation time. This peak results from the crossover between the degenerate and nondegenerate limits. We also find that the in-plane spin relaxation time decreases rapidly with the increase of the initial spin polarization at low temperature, which is the same as the situation in bilayer graphene but opposite to the cases of both semiconductors and single-layer graphene.
View original:
http://arxiv.org/abs/1305.3361
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