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

• 作者: Kejing Ran Jinghui Wang Song Bao Zhengwei Cai Yanyan Shangguan Zhen Ma Wei Wang Zhao-Yang Dong P.(C)ermák A.Schneidewind Siqin Meng Zhilun Lu Shun-Li Yu Jian-Xin Li Jinsheng Wen
• 来源期刊: 中国物理快报（英文版）
• 年，卷（期）: 2022,（2）
• 所属期刊栏目: CONDENSED MATTER:ELECTRONIC STRUCTURE,ELECTRICAL,MAGNETIC,AND OPTICAL PROPERTIES
• 页码范围: 93-98
• 页数: 6页
• 语种: 英文
• DOI: 10.1088/0256-307X/39/2/027501

摘要

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 Γpoint 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.