Influence of anisotropy, tilt and pairing of Weyl nodes: The Weyl semimetals TaAs, TaP, NbAs and NbP

Abstract

By means of $abinitio$ band structure methods and model Hamiltonians we investigate the electronic, spin and topological properties of four monopnictides crystallizing in body centered tetragonal structure. We show that the Weyl bands around a Weyl point W1 or W2 possess a strong anisotropy and tilt of the accompanying Dirac cones. These effects are larger for W2 nodes than for W1 ones. The node tilts and positions in energy space significantly influence the density of states of single-particle Weyl excitations. The node anisotropies destroy the conventional picture of (anti)parallel spin and wave vector of a Weyl fermion. This also holds for the Berry curvature around a node, while the monopole charges are independent as integrated quantities. The pairing of the nodes strongly modify the spin texture and the Berry curvature for wave vectors in between the two nodes. Spin components may change their orientation. Integrals over planes perpendicular to the connection line yield finite Zak phases and winding numbers for planes between the two nodes, thereby indicating the topological character.

References in corpus (9)

• Topological Semimetals
• Excitonic Effects on the Optical Response of Graphene and Bilayer Graphene
• Weyl Semimetals, Fermi Arcs and Chiral Anomalies (A Short Review)
• Photocurrents in Weyl semimetals
• Quantum Transport in Topological Semimetals under Magnetic Fields
• Distinct evolutions of Weyl fermion quasiparticles and Fermi arcs with bulk band topology in Weyl semimetals
• Detection of topological phase transitions through entropy measurements: the case of germanene
• Weyl nodes as topological defects of the Wannier-Stark ladder: From surface to bulk Fermi arcs
• Hidden type-II Weyl points in the Weyl semimetal NbP