Evidence for field induced quantum spin liquid behavior in a spin-1/2 honeycomb magnet

One of the most important issues in modern condensed matter physics is the realization of fractionalized excitations, such as the Majorana excitations in the Kitaev quantum spin liquid. To this aim, the 3d-based Kitaev material Na₂Co₂TeO₆ is a promising candidate whose magnetic phase diagram of B // a* contains a field-induced intermediate magnetically disordered phase within 7.5 T < |B| < 10 T. The experimental observations, including the restoration of the crystalline point group symmetry in the angle-dependent torque and the coexisting magnon excitations and spinon-continuum in the inelastic neutron scattering spectrum, provide strong evidence that this disordered phase is a field induced quantum spin liquid with partially polarized spins. Our variational Monte Carlo simulation with the effective K-J₁-Γ-Γ'-J₃ model reproduces the experimental data and further supports this conclusion.. Authors: Lin, Gaoting [Shanghai Jiao Tong Univ. (China)]; Shu, Mingfang [Shanghai Jiao Tong Univ. (China); Guangdong Provincial Key Laboratory of Extreme Conditions, Dongguan (China)]; Zhao, Qirong [Renmin Univ. of China, Beijing (China)]; Li, Gang [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics]; Ma, Yinina [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics]. DOE Contract: AC05-00OR22725; SC0020184. Subjects: 36 MATERIALS SCIENCE; Kitaev quantum spin liquid; bond-dependent frustrated magnet; honeycomb lattice; quantum fluctuations under magnetic fields