Momentum-Space Spin Antivortex and Spin Transport in Monolayer Pb

Nontrivial 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 the spin Hall effect. In this work, we find a nontrivial spin texture, spin antivortex, can appear at certain momenta on the ?? ??? K line in a 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 antivortex is guaranteed by the Poincare??-Hopf theorem and thus topologically stable. Accompanied with this spin antivortex, a Lifshitz transition of Fermi surfaces occurs at certain momenta on the K ??? M line, and both phenomena are originated from the anticrossing between the j = 1/2 and j = 3/2 bands. A rapid variation of the response coefficients for both the currentinduced spin polarization and spin Hall conductivity is found when the Fermi energy is tuned around the spin antivortex. Our work demonstrates the monolayer Pb as a potentially appealing platform for spintronic applications.

Automated summary

This work discovers a nontrivial spin texture, spin antivortex, on a 2D monolayer Pb on SiC substrate and demonstrates its topological stability. It also observes the Lifshitz transition of Fermi surfaces and rapid variation of response coefficients.