Abstract
The Kitaev model, a honeycomb network of spins with bond-dependent anisotropic interactions, is a rare example of a system with a quantum spin liquid ground state. Although most Kitaev model candidate materials eventually order magnetically due to additional non-Kitaev interactions, their bond-dependent anisotropy manifests in unusual spin dynamics. Recent research suggests that bond-dependent anisotropy can stabilize exotic magnetic phases on the geometrically frustrated triangular lattice. Unfortunately, few materials have been identified with simultaneous geometric frustration and bond-dependent anisotropy. Here, we report a frustrated triangular lattice with bond-dependent anisotropy in the cobalt-based van der Waals antiferromagnet CoI2. Momentum and energy-resolved inelastic neutron scattering measurements show substantial magnon decay and level repulsion. A thorough examination of excitations in both the paramagnetic and magnetically ordered states demonstrates that the bond-dependent anisotropy is the origin of the spiral order and the magnon decay found in CoI2. Our results provide the basis for future studies of the interplay between Kitaev magnetism and geometric frustration.
| Original language | English |
|---|---|
| Pages (from-to) | 1624-1629 |
| Number of pages | 6 |
| Journal | Nature Physics |
| Volume | 19 |
| Issue number | 11 |
| DOIs | |
| State | Published - Nov 2023 |
| Externally published | Yes |
Funding
We thank P. Maksimov, K. Barros, M. Willson and C. D. Batista for fruitful discussions. This work was supported by the Leading Researcher Program of the National Research Foundation of Korea (Grant No. 2020R1A3B2079375). The INS experiment was performed at the MLF of J-PARC under a user program (Proposal No. 2020B0407). The work of A.L.C. was supported by the US Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0021221. The work of M.M. was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division under award DE-SC-0018660. The work of S.K. and S.-J.K was supported by the Pioneer Research Center Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (NRF-2022M3C1A309198811).