Abstract
The discovery of massless Dirac electrons in graphene and topological Dirac-Weyl materials has prompted a broad search for bosonic analogues of such Dirac particles. Recent experiments have found evidence for Dirac magnons above an Ising-like ferromagnetic ground state in a two-dimensional (2D) kagome lattice magnet and in the van der Waals layered honeycomb crystal CrI3, and in a 3D Heisenberg magnet Cu3TeO6. Here, we report our inelastic neutron scattering investigation on a large single crystal of a stacked honeycomb lattice magnet CoTiO3, which is part of a broad family of ilmenite materials. The magnetically ordered ground state of CoTiO3 features ferromagnetic layers of Co2+, stacked antiferromagnetically along the c axis. The magnon dispersion relation is described very well with a simple magnetic Hamiltonian with strong easy-plane exchange anisotropy. Importantly, a magnon Dirac cone is found along the edge of the 3D Brillouin zone. Our results establish CoTiO3 as a model pseudospin-1/2 material to study interacting Dirac bosons in a 3D quantum XY magnet.
| Original language | English |
|---|---|
| Article number | 011062 |
| Journal | Physical Review X |
| Volume | 10 |
| Issue number | 1 |
| DOIs | |
| State | Published - Mar 2020 |
Funding
Work at the University of Toronto was supported by the Natural Science and Engineering Research Council (NSERC) of Canada. F. C. C. acknowledges funding support from the Ministry of Science and Technology (MOST) in Taiwan under Projects No. 106-2119-M-002-035-MY3 and No. 108-2622-8-002-016, AI-MAT Project No. 108L900903 from the Ministry of Education in Taiwan, and Academia Sinica (AS-iMATE-108-11). G. J. S. acknowledges the support provided by MOST-Taiwan under Project No. 108-2112-M-027-002-MY3. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Use of the MAD beamline at the McMaster Nuclear Reactor is supported by McMaster University and the Canada Foundation for Innovation. MOST-Taiwan under Project No.108-2112-M-027-002-MY3. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.
| Funders | Funder number |
|---|---|
| AI-MAT | 108L900903 |
| Ministry of Education in Taiwan | |
| Office of Science | |
| Oak Ridge National Laboratory | |
| McMaster University | |
| Natural Sciences and Engineering Research Council of Canada | |
| Canada Foundation for Innovation | |
| Academia Sinica | AS-iMATE-108-11 |
| Ministry of Science and Technology | 106-2119-M-002-035-MY3, 108-2622-8-002-016 |
| Ministry of Science and Technology, Taiwan | 108-2112-M-027-002-MY3 |