  Topological nodal semimetals are known to host a variety of fascinating
electronic properties due to the topological protection of the band-touching
nodes. Neutron scattering, despite its power in probing elementary excitations,
has not been routinely applied to topological semimetals, mainly due to the
lack of an explicit connection between the neutron response and the signature
of topology. In this work, we theoretically investigate the role that neutron
scattering can play to unveil the topological nodal features: by passing
through an electric current, a large magnetic neutron response with spectral
non-analyticity can be generated solely from the nodal bands. A new formula for
the dynamical structure factor for generic topological nodal metals is derived.
For Weyl semimetals, we show that the locations of Weyl nodes, the Fermi
velocities and the signature of chiral anomaly can all leave hallmark neutron
spectral responses. Our work offers a neutron-based avenue towards probing bulk
topological materials.
