Magnetic Interactions and Novel Weyl State in Co3Sn2S2

January 4, 2022
Magnetic Interactions and Novel Weyl State in Co3Sn2S2
(Left) Magnetic excitations near the (-1,1,1) zone center. Solid line is the best fit dispersion. (Right) Illustration of the Kagome lattice of Co magnetic moments together with possible exchange interactions. The dominant third-neighbor “across-hexagon" exchange interaction is labeled as Jd.

Scientific Achievement

Surprisingly, it is shown that the ferromagnetic (FM) ground state in the magnetic Weyl semimetal Co3Sn2S3 with magnetic Co ions on a Kagome lattice is stabilized by the third-neighbor “across-hexagon" interaction.

Significance and Impact

This work demonstrates that in Kagome lattice materials, long-range magnetic interactions are important elements leading to distinct magnetic orders as well as magnetic Weyl states.

Research Details

  • Neutron powder diffraction is used to determine the crystal and magnetic structures.
  • Inelastic neutron scattering is used to determine the exchange couplings in the ferromagnetic ground state.
  • Data and dispersions were fit to spin wave theory.
  • Exchange constants are also extracted from two density functional theory-based methods: constrained magnetics and multiple-scattering Green’s function methods.

“Unusual Exchange Couplings and Intermediate Temperature Weyl State in Co3Sn2S2”

Qiang Zhang, Satoshi Okamoto, German D. Samolyuk, Matthew B. Stone, Alexander I. Kolesnikov, Rui Xue, Jiaqiang Yan, Michael A. McGuire, David Mandrus, and D. Alan Tennant

Physical Review Letters 127, 117201 (2021). DOI: 10.1103/PhysRevLett.127.117201