Tuning the intrinsic spin Hall effect by charge density wave order in topological kagome metals

Kagome metals are topological materials with a rich phase diagram featuring various charge density wave orders and even unconventional superconductivity. However, little is still known about possible spin polarized responses in these nonmagnetic compounds. Here, we perform ab initio calculations of the intrinsic spin Hall effect (SHE) in the kagome metals $A{\mathrm{V}}₃{\mathrm{Sb}}₅$ ($A=\mathrm{Cs}$, Rb, K), ${\mathrm{CsTi}}₃{\mathrm{Bi}}₅$, and ${\mathrm{ScV}}₆{\mathrm{Sn}}₆$. We report large spin Hall conductivities, comparable with the Weyl semimetal TaAs. Additionally, in ${\mathrm{CsV}}₃{\mathrm{Sb}}₅$ the SHE is strongly renormalized by the charge density wave order. We can understand these results based on the topological properties of band structures, demonstrating that the SHE is dominated by the position and shape of the Dirac nodal lines in the kagome sublattice. Our results suggest kagome materials as a promising, tunable platform for future spintronics applications.