Magnetic field-dependent low-energy magnon dynamics in α – RuCl 3
Name
PhysRevB.100.085108.pdf
Description
Published version
Size
888.3 KB
Format
Adobe PDF
Checksum (MD5)
3d4670005cabe0505902e526c8ece229
Author(s)
Ozel, Ilkem Ozge
Belvin, Carina A
Baldini, Edoardo
Kimchi, Itamar
Do, Seunghwan
Choi, Kwang-Yong
Gedik, Nuh
Date Issued
2019
Journal
Physical Review B
Publisher
American Physical Society (APS)
Version
Final published version
Abstract
© 2019 American Physical Society. Revealing the spin excitations of complex quantum magnets is key to developing a minimal model that explains the underlying magnetic correlations in the ground state. We investigate the low-energy magnons in α-RuCl3 by combining time-domain terahertz spectroscopy under an external magnetic field and model Hamiltonian calculations. We observe two absorption peaks around 2.0 and 2.4 meV, which we attribute to zone-center spin waves. Using linear spin-wave theory with only nearest-neighbor terms of the exchange couplings, we calculate the antiferromagnetic resonance frequencies and reveal their dependence on an external field applied parallel to the nearest-neighbor Ru-Ru bonds. We find that the magnon behavior in an applied magnetic field can be understood only by including an off-diagonal Γ exchange term to the minimal Heisenberg-Kitaev model. Such an anisotropic exchange interaction that manifests itself as a result of strong spin-orbit coupling can naturally account for the observed mixing of the modes at higher fields strengths.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PHYSREVB.100.085108
