Weyl semimetals are solid-state crystals that carry electrical charge at room temperature due to the presence of particles called Weyl fermions. Mn₃Sn is a magnetic Weyl semimetal attracting considerable research attention. An international team of researchers has used inelastic neutron scattering on the MERLIN time-of-flight spectrometer to measure the full spin wave spectra of Mn₃Sn over a wide range of momentum and energy. They then used a linear spin wave theory to create a theoretical model that explains their results and is consistent with density functional theory calculations.

Their work, published in npj Quantum Materials, provides an unusual example of a topological phenomenon (the Weyl point) being removed by a slight change to the magnetic ground state, demonstrating the close coupling between the spin and electronic degrees of freedom in Mn₃Sn.

Related publication: “Magnetic excitations in non-collinear antiferromagnetic Weyl semimetal Mn3Sn" npj Quantum Materials, Volume 3, Article number: 63 (2018), DOI: 10.1038/s41535-018-0137-9

Authors: Pyeongjae Park (Institute for Basic Science, Seoul; Seoul National University), Joosung Oh (Institute for Basic Science, Seoul; Seoul National University), Klára Uhlířová (Charles University in Prague), Jerome Jackson (SCD, STFC), András Deák (Budapest University of Technology and Economics), László Szunyogh (Budapest University of Technology and Economics), Ki Hoon Lee (Institute for Basic Science, Seoul; Seoul National University), Hwanbeom Cho (Institute for Basic Science, Seoul; Seoul National University), Ha-Leem Kim (Seoul National University), Helen C. Walker (ISIS), Devashibhai Adroja (ISIS; University of Johannesburg), Vladimír Sechovský (Charles University in Prague), Je-Geun Park (Institute for Basic Science, Seoul; Seoul National University).