Weyl fermions are relativistic particles that could emerge in condensed matter materials. They have been intensely studied for their electronic properties but it was not clear whether they can participate in magnetic interactions too. Tafti Lab graduate student, Xiaohan Yao, has found evidence of Weyl-mediated magnetism in the non-centrosymmetric crystals of SmAlSi. She made a case for spiral ordering mediated by Weyl fermions using a combination of neutron scattering and transport experiments. This work shows a new mechanism to create spiral order and topological magnetic excitations by engaging Weyl fermions in magnetic interactions.
