Abstract
Recent advances in the study of cobaltites have unveiled their potential as a promising platform for realizing Kitaev physics in honeycomb systems and the Ising model in weakly coupled chain materials. In this manuscript, we explore the magnetic properties of pyroxene SrCoGe2O6 using a combination of neutron scattering, ab initio methods, and linear spin-wave theory. Through careful examination of inelastic neutron scattering powder spectra, we propose a modified Kitaev model to accurately describe the twisted chains of edge-sharing octahedra surrounding Co2+ ions. The extended Kitaev-Heisenberg model, including a significant anisotropic bonddependent exchange term with K =jJ j = 0:96, is identified as the key descriptor of the magnetic interactions in SrCoGe2O6. Furthermore, our heat capacity measurements reveal an effect of an external magnetic field (approximately 13 T) which shifts the system from a fragile antiferromagnetic ordering with TN = 9 K to a field-induced state. We argue that pyroxenes, particularly those modified by substituting Ge with Si and its less extended p orbitals, emerge as a platform for the Kitaev model. This opens up possibilities for advancing our understanding of Kitaev physics.
| Original language | English |
|---|---|
| Article number | e2409154121 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 121 |
| Issue number | 43 |
| DOIs | |
| State | Published - Oct 22 2024 |
Funding
We thank Jong Keum for assistance with X-ray measurements. We also would like to thank Sasha Chernyshev for useful discussions. Work at Oak Ridge National Laboratory (ORNL) was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. X-ray was conducted at the Center for NanophaseMaterialsSciences(CNMS)(CNMS2019-R18)atORNL, whichisaDOE Office of Science User Facility. Magnetization measurements were conducted as part of a user project at CNMS, which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. Theoretical calculations of P.A.M., A.V.U., and S.V.S. were supported by the Russian Science Foundation via project RSF 23-12-00159, A.F.G. thanks to program 122021000031-8 (Flux).
Keywords
- Kitaev model
- frustrated magnetism
- inelastic neutron scattering
- pyroxenes