Regensburg 2025 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 7: INNOMAG e.V. Prizes 2025 (Diplom-/Master and Ph.D. Thesis)
MA 7.2: Hauptvortrag
Montag, 17. März 2025, 15:20–15:40, H18
Low-energy spin excitations of the Kitaev candidate material Na2Co2TeO6 probed by high-field/high-frequency electron spin resonance spectroscopy — •Luca Bischof1, Jan Arneth1, Kwang-Yong Choi2, Raju Kalaivanan3, Raman Sankar3, and Rüdiger Klingeler1 — 1Kirchhoff Institute for Physics, Heidelberg University, Germany — 2Department of Physics, Sungkyunkwan University, Republic of Korea — 3Institute of Physics, Academia Sinica, Taiwan
The realization of a Kitaev spin liquid state in the Co-based honeycomb magnet Na2Co2TeO6 is circumvented by magnetic ordering due to Heisenberg and off-diagonal interactions. The nature of these interactions and the magnetic ground state in Na2Co2TeO6 are still under debate. We report high-frequency/high-field electron spin resonance (ESR) measurements of single-crystal Na2Co2TeO6 probing the low-energy spin excitations of the ordered phase below TN ≃ 27 K. A complex magnon spectrum for in-plane magnetic fields B∥ a* indicates field-induced phase transitions. For out-of-plane magnetic fields B∥ c, we observe one softening and two hardening magnon modes. They share a magnon excitation gap of Δ = 219(13) GHz. We performed spin wave calculations for the extended Heisenberg-Kitaev model to compare the observed magnon modes to the low-energy excitations expected for zigzag and triple-q ground states in an applied magnetic field.
Keywords: Kitaev materials; High-field/high-frequency electron spin resonance; Spin excitations; Kitaev-Heisenberg model; Linear spin wave theory