Figure 3: Weyl points and topological chiral charges in TaAs.
From: A Weyl Fermion semimetal with surface Fermi arcs in the transition metal monopnictide TaAs class
(a) In the absence of spin–orbit coupling, there are two line nodes on the kx=0 mirror plane, Mx, and two line nodes on the ky=0 mirror plane, My. In the presence of spin–orbit coupling, each line node vaporizes into six Weyl points. The Weyl points are denoted by small circles. Black and white show the opposite chiral charges of the Weyl points. (b) The band structure around one of the red line nodes in the absence of spin–orbit coupling. (c) The band structure near one of the Weyl points at kxa=0.01π in the presence of spin–orbit coupling. The Weyl point is shifted away from the kx=0 mirror plane. (d) The projection of the bulk Weyl points around the 
line. (e) A schematic for the projection of all the Weyl points on the (001) surface Brillouin zone. We denote the eight Weyl points that are located on the kz=2Ï€/c plane as W1 (1) and the other sixteen Weyl points as W2 (2). (f) Calculated spin texture (Sy,Sz) in the vicinity of two Weyl points with opposite chiral charges.
