Internodal tunnelling and magnetotransport in Weyl semimetals

Internodal dynamics of quasiaprticles in Weyl semimetals manifests itself in hydrodynamic, transport and thermodynamic phenomena and is essential for potential valleytronic applications of these systems. Charge transfer between the nodes in a Weyl semimetal is often considered as an inelastic process, with the charge carriers quickly thermalising at each node. In an external magnetic field, however, coherent quasipaticle tunnelling between the nodes may lead to a significant modification of the quasiparticle dispersion in a clean Weyl semimetal for certain directions of the magnetic field. In particular, it results in the opening of a gap in the quasiparicle dispersion, whose magnitude depends exponentially on the magnetic field. We study the interplay of such tunnelling with magnetotransport in a Weyl semimetal. We compute microscopically the longitudal resistivity of a disordered Weyl semimetal with two nodes in a strong magnetic field and demonstrate that it has a strong angular dependence ρ(η)∼C₁ + C₂ cos²η, where η is the angle between the field and the line connecting the nodes. The first term is determined by the coherent internodal coupling and depends exponentially on the magnetic field, while the second term is independent of this coupling.