Probing Weyl nodes by inelastic neutron scattering

We present how to detect Weyl nodes in a material by inelastic neutron scattering, taking into account realistic anisotropic properties. A generic material will not have relativistic symmetry. However, under circumstances not too limiting, the dynamics of the excitations can be mapped to a relativistic symmetry. It is then possible to separate out universal properties reflecting this in the cross-section. In a fully unpolarized experiment it is possible to detect the spin-momentum locking of Weyl states, their linear dispersion, principal axis and a sum-rule independent of the material parameters. Furthermore, with polarized neutrons, it is possible to experimentally control the momentum and spin of the excited Weyl particle-hole pairs, with the consequence that the scattered neutron beam is fully polarized in a direction determined by the coupling parameters of the material. This allows one to determine cleanly the coupling parameters as well as to measure the chirality of the Weyl nodes involved in the scattering.