Weyl nodes of opposite chirality connected by topological Fermi arcs
Weyl semimetals host topologically protected band-crossing points (Weyl nodes) with quantized Berry phase ±2π. Nodes come in pairs of opposite chirality (chiral monopoles of Berry curvature); their surface projections are connected by topological Fermi arc states. The chiral anomaly causes parallel E and B fields to pump charge between nodes: j ~ E·B. Discovered in TaAs (2015).