  Quantum materials with strong transport responses to disparate physical
quantities are of great fundamental significance and may hold technological
potentials. The interplay between interactions and topology drive such
responses through the effects of spontaneous symmetry breaking and the
associated domain configurations on quantum transport. Here we provide a
comprehensive description of the magnetism of Mn3Ge, an antiferromagnetic
kagomebased semimetal with room temperature transport anomalies associated with
topologically protected Weyl nodes. Using polarized neutron diffraction, we
show the all-important magnetic structure is anti-chiral and coplanar carrying
the symmetry of a ferromagnet without appreciable magnetization. We probe and
classify the long wavelength excitations that determine its macroscopic
responses including a set of collective magneto-elastic modes. We develop a
phenomenological spin Hamiltonian with exchange, Dzyaloshinskii-Moriya, and
crystal field interactions to describe its collective magnetism. The itinerant
character of the magnetism that drives quantum transport is apparent in spin
wave damping and extended magnetic interactions. Our work provides the
scientific basis for manipulation of the chiral antiferromagnetic texture of
Mn3Ge to control its topological quantum transport.
