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Evidence for Magnetic Fractional Excitations in a Kitaev Quantum-Spin-Liquid Candidate α-RuCl3


Kejing Ran

Jinghui Wang

Bao Song

Zhengwei Cai

Yanyan Shangguan

Zhen Ma

Wei Wang

Zhao-Yang Dong


A. Schneidewind

Siqin Meng

Shun-Li Yu

Jian-Xin Li

Jinsheng Wen


It is known that α-RuCl3 has been studied extensively because of its proximity to the Kitaev quantum-spin-liquid (QSL) phase and the possibility of approaching it by tuning the competing interactions. Here we present the first polarized inelastic neutron scattering study on α-RuCl3 single crystals to explore the scattering continuum around the Γ point at the Brillouin zone center, which was hypothesized to be resulting from the Kitaev QSL state but without concrete evidence. With polarization analyses, we find that, while the spin-wave excitations around the M point vanish above the transition temperature TN, the pure magnetic continuous excitations around the Γ point are robust against temperature. Furthermore, by calculating the dynamical spin-spin correlation function using the cluster perturbation theory, we derive magnetic dispersion spectra based on the K–Γ model, which involves with a ferromagnetic Kitaev interaction of −7.2 meV and an off-diagonal interaction of 5.6 meV. We find this model can reproduce not only the spin-wave excitation spectra around the M point, but also the non-spin-wave continuous magnetic excitations around the Γ point. These results provide evidence for the existence of fractional excitations around the Γ point originating from the Kitaev QSL state, and further support the validity of the K–Γ model as the effective minimal spin model to describe α-RuCl3.


Ran, K., Wang, J., Song, B., Cai, Z., Shangguan, Y., Ma, Z., …Wen, J. (2022). Evidence for Magnetic Fractional Excitations in a Kitaev Quantum-Spin-Liquid Candidate α-RuCl3. Chinese Physics Letters, 39(2), Article 027501.

Journal Article Type Article
Acceptance Date Dec 24, 2021
Online Publication Date Dec 27, 2021
Publication Date 2022
Deposit Date Dec 29, 2021
Print ISSN 0256-307X
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 39
Issue 2
Article Number 027501
Public URL