Spin-wave excitations in the antiferromagnetic Weyl semimetal candidates Mn3Ge and Mn3Sn*

Mn3X ( with X = Ge or Sn) are semimetal antiferromagnets with large anomalous Hall and Nernst effects. These anomalous transport properties have been attributed to the presence of electronic Weyl nodes near the Fermi energy of these materials [1,2]. The magnetism of Mn3X remains relatively unexplored. For example, a detail knowledge of their magnetic excitations is still lacking. In this talk, we report the inelastic neutron scattering spectra of Mn3Ge and Mn3Sn. Our analysis reveals linear dispersive modes that are gapped by ~ 5 meV and have an energy bandwidth of ~ 80 meV. Spin Hamiltonians for both Mn3Sn and Mn3Ge have been derived and will be presented along with a detailed comparison between the two sister compounds. [1] S. Nakasutji et al., Nature 527, p.212–215 (2015) [2] M. Iklhas et al., Nature Physics 13, p. 1085–1090 (2017)