🍩 Database of Original & Non-Theoretical Uses of Topology

1. Topological Electronic Structure and Weyl Points in Nonsymmorphic Hexagonal Materials (2020)

   Rafael González-Hernández, Erick Tuiran, Bernardo Uribe

   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.

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   • Material science
   • Mesoscale physics
   • Nanoscale physics
   • Berry curvature
   • Chirality
   • Topological band theory
   • Topological charge