Unconventional magnons in collinear magnets dictated by spin space groups

Magnonic systems provide a fertile playground for bosonic topology1, for example, Dirac2–6 and Weyl7,8 magnons, leading to a variety of exotic phenomena such as charge-free topologically protected boundary modes6,7, the magnon thermal Hall effect9 and the magnon spin Nernst effect10. However, their understanding has been hindered by the absence of fundamental symmetry descriptions of magnetic geometries and spin Hamiltonians primarily governed by isotropic Heisenberg interactions. The ensuing magnon dispersions enable gapless magnon band nodes that go beyond the scenario of representation theory of the magnetic space groups11,12, thus referred to as unconventional magnons. Here we developed spin space…

• NN
  National Natural Science Foundation of China

  Awards: 2020KCXTD001, 2020YFA0308900, 12274194, 2019B030301001
• ST
  Science, Technology and Innovation Commission of Shenzhen Municipality

  Awards: 20231117091158001, ZDSYS20190902092905285
• SU
  Southern University of Science and Technology

  Award: 2019B030301001