Dirac Magnon in a Honeycomb Quantum XY Magnet CoTiO3

August 31, 2020
Dirac Magnon in a Honeycomb Quantum XY Magnet CoTiO3
(Left) Crystal structure of CoTiO3. (Right) Spectrum of magnetic excitations in CoTiO3 highlighting a Dirac cone-like dispersion passing through the K point (red circle).

Scientific Achievement

The spectrum of magnons in the pseudospin-½ honeycomb XY magnet CoTiO3 is shown to exhibit a Dirac cone, analogous to Dirac electrons in graphene.

Significance and Impact

This work establishes CoTiO3 as a simple model material ideal for studying topological magnons that eventually may find applications for new spintronic technologies.

Research Details

  • Inelastic neutron scattering was used to measure the single-ion levels of Co2+ in CoTiO3, establishing the effective spin ½ ground state.
  • The energy-momentum dependence of the collective spin excitations in the ordered phase of CoTiO3 revealed Dirac magnons near the edge of Brillouin zone.
  • Spin wave calculations using an XXZ Hamiltonian with near-neighbor intraplane / next-near-neighbor interplane interactions can reproduce the observed spin excitations.   

“Dirac magnons in a honeycomb lattice quantum XY magnet CoTiO3” 
Bo Yuan, Ilia Khait, Guo-Jiun Shu, F. C. Chou, M. B.Stone, J. P. Clancy, Arun Paramekanti, and Young-June Kim, 
Physical Review X, 10, 011062 (2020). 
DOI: https://doi.org/10.1103/PhysRevX.10.011062