Journal Article

FZJ-2021-06214

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Evidence for Magnetic Fractional Excitations in a Kitaev Quantum-Spin-Liquid Candidate α-RuCl3

Ran, K. ; Wang, J. ; Bao, S. ; Cai, Z. ; Shangguan, Y. ; Ma, Z. ; Wang, W. ; Dong, Z.-Y. ; Cermak, P. ; Schneidewind, A.FZJ* ; Meng, S. ; Lu, Z. ; Yu, S.-L. ; Li, J.-X. ; Wen, J. (Corresponding author)

2022
IOP Publ. Bristol

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Please use a persistent id in citations: http://hdl.handle.net/2128/30267  doi:10.1088/0256-307X/39/2/027501

Abstract: 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 firstpolarized inelastic neutron scattering study on 𝛼-RuCl3 single crystals to explore the scattering continuum aroundthe 𝛤 point at the Brillouin zone center, which was hypothesized to be resulting from the Kitaev QSL state butwithout concrete evidence. With polarization analyses, we find that, while the spin-wave excitations around the𝑀 point vanish above the transition temperature 𝑇N, the pure magnetic continuous excitations around the 𝛤point are robust against temperature. Furthermore, by calculating the dynamical spin-spin correlation functionusing the cluster perturbation theory, we derive magnetic dispersion spectra based on the 𝐾–𝛤 model, whichinvolves with a ferromagnetic Kitaev interaction of −7.2meV and an off-diagonal interaction of 5.6 meV. We findthis model can reproduce not only the spin-wave excitation spectra around the 𝑀 point, but also the non-spinwavecontinuous magnetic excitations around the 𝛤 point. These results provide evidence for the existence offractional excitations around the 𝛤 point originating from the Kitaev QSL state, and further support the validityof the 𝐾–𝛤 model as the effective minimal spin model to describe 𝛼-RuCl3.

Keyword(s): Magnetic Materials (1st) ; Magnetism (2nd) ; Condensed Matter Physics (2nd)

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Contributing Institute(s):

1. JCNS-FRM-II (JCNS-FRM-II)
2. Streumethoden (JCNS-2)
3. JCNS-4 (JCNS-4)
4. Heinz Maier-Leibnitz Zentrum (MLZ)
5. Streumethoden (PGI-4)
6. JARA-FIT (JARA-FIT)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. 6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ) (POF4-6G4) (POF4-6G4)

Experiment(s):

1. PANDA: Cold three axes spectrometer (SR2)

Appears in the scientific report 2022

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; National-Konsortium ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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