Non-trivial momentum-space spin texture of electrons can be induced by spin-orbit coupling and underpins various spin transport phenomena, such as current-induced spin polarization and spin Hall effect. In this work, we find a non-trivial spin texture, spin anti-vortex, can appear at certain momenta on the Γ−K line in 2D monolayer Pb on top of SiC. Different from spin vortex due to the band degeneracy in the Rashba model, the existence of this spin anti-vortex is guaranteed by Poincare-Hopf theorem and thus topologically stable. Accompanied with this spin anti-vortex, a Lifshtiz transition of Fermi surfaces occur at certain momenta on the K−M line, and both phenomena are originated from the anti-crossing between the j=1/2 and j=3/2 bands. A rapid variation of the response coefficients for both the current-induced spin polarization and spin Hall conductivity is found when the Fermi energy is tuned around the spin anti-vortex. Our work demonstrates the monolayer Pb as a potentially appealing platform for spintronic applications.
@article{arxiv.2110.08968,
title = {Momentum-Space Spin Antivortex and Spin Transport in Monolayer Pb},
author = {Kaijie Yang and Yuanxi Wang and Chao-Xing Liu},
journal= {arXiv preprint arXiv:2110.08968},
year = {2022}
}