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.

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

School of Physical Science and Technology,and ShanghaiTech Laboratory for Topological Physics,ShanghaiTech University,Shanghai 200031,China;National Laboratory of Solid State Microstructures and Department of Physics,Nanjing University,Nanjing 210093,China;Institute for Advanced Materials,Hubei Normal University,Huangshi 435002,China;School of Science,Nanjing University of Posts and Telecommunications,Nanjing 210023,China;Department of Applied Physics,Nanjing University of Science and Technology,Nanjing 210094,China;Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ),Forschungszentrum Jülich GmbH,Lichtenbergstr.1,85748 Garching,Germany;Charles University,Faculty of Mathematics and Physics,Department of Condensed Matter Physics,Ke Karlovu 5,12116,Praha,Czech Republic;Helmholtz-Zentrum Berlin für Materialien und Energie GmbH,Hahn-Meitner-Platz 1D-14109,Berlin,Germany;China Institute of Atomic Energy (CIAE),Beijing 102413,China;The Henry Royce Institute and Department of Materials Science and Engineering,The University of Sheffield,Sir Robert Hadfield Building,Sheffield,S13JD,United Kingdom;Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China

中国物理快报（英文版）

[1]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-.Evidence for Magnetic Fractional Excitations in a Kitaev Quantum-Spin-Liquid Candidate α-RuCl3)[J].中国物理快报（英文版）,2022(02):93-98

Evidence,Magnetic,Fractional,Excitations,Kitaev,Quantum,Spin,Liquid,Candidate,RuCl3,It,known,that,been,studied,extensively,because,its,proximity,quantum,spin,liquid,QSL,phase,possibility,approaching,by,tuning,competing,interactions,Here,we,present,first,polarized,inelastic,neutron,scattering,study,single,crystals,explore,continuum,around,point,Brillouin,zone,center,which,was,hypothesized,resulting,from,state,but,without,concrete,evidence,With,polarization,analyses,find,while,wave,excitations,vanish,above,transition,temperature,TN,pure,continuous,are,robust,against,Furthermore,calculating,dynamical,correlation,function,using,cluster,perturbation,theory,derive,dispersion,spectra,model,involves,ferromagnetic,meV,off,diagonal,We,this,can,reproduce,not,only,also,These,results,provide,existence,fractional,originating,further,support,validity,effective,minimal,describe

0.576159