Item

Abstract

Using topological band theory analysis we show that the nonsymmorphic
symmetry operations in hexagonal lattices enforce Weyl points at the
screw-invariant high-symmetry lines of the band structure. The corepresentation
theory and connectivity group theory show that Weyl points are generated by
band crossings in accordion-like and hourglass-like dispersion relations. These
Weyl points are stable against weak perturbations and are protected by the
screw rotation symmetry. Based on first-principles calculations we found a
complete agreement between the topological predicted energy dispersion
relations and real hexagonal materials. Topological charge (chirality) and
Berry curvature calculations show the simultaneous formation of Weyl points and
nodal-lines in 4d transition-metal trifluorides such as AgF3 and AuF3.
Furthermore, a large intrinsic spin-Hall conductivity was found due to the
combined strong spin-orbit coupling and multiple Weyl-point crossings in the
electronic structure. These materials could be used to the spin/charge
conversion in more energy-efficient spintronic devices.