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We propose a spin Hall effect (SHE) enhancement mechanism due to Kramers-Weyl point (KWP) alignment in chiral topological semimetals with high Chern numbers (CNs). Through model Hamiltonian calculations, we identify enhancements in the intrinsic spin Hall conductivity (SHC) and the spin Hall angle (SHA). Such enhancements, attributed to a unique high CN KWP energetic alignment and a high degree of SOC-induced band nesting, strongly depend on orbital-orbital interactions. This represents a novel mechanism to enhance SHE, differing from the spin-orbit induced anticrossing mechanism in gapped systems. Guided by this principle, we corroborate our results by means of first-principles calculations and reveal multiple realistic materials with large intrinsic SHCs and even larger SHAs than Pt., Comment: 6 pages, 4 figures

We investigate the plasmons in bilayer black phosphorus (BP) with bias-driven formation of Dirac cones, by developing an effective two-band Hamiltonian that captures this electronic transition with great accuracy. We show that the appearance of the Dirac cones lead to additional linearly dispersing acoustic plasmon mode, in conjunction to the conventional plasmon. In addition, the change in the Fermi surface topology from a disc to ring or dual pockets also modifies the dielectric loss., Comment: 5 pages, 3 figures