Novel ground state in the honeycomb-lattice antiferromagnet Co2Te3O8

Frustrated magnets wherein competing magnetic interactions between spins induce strong quantum fluctuations have attracted intensive attention in view of realizing exotic magnetic phases with anisotropic interactions, quasi-particle fractionalization, and long-range entanglement. Of particular interest, enormous efforts have been devoted towards the experimental realization of emergent quasi-particle excitations such as spinons with the signature of quantum entanglement even in the magnetically ordered state. Alexei Kitaev proposed an exactly solvable highly anisotropic Kitaev model for S = 1/2 spins on the honeycomb spin-lattice. Contrary to an isotropic nearest-neighbor exchange model on the honeycomb-lattice, which exhibits long-range order, the ground state of the Kitaev model is a quantum spin liquid (QSL) with fractionalized Majorana fermions and gauge flux excitations. Here, we focus on a new Co2+ structurally perfect honeycomb lattice antiferromagnet that shows an antiferromagnetic ordering at 53 K. The magnetic entropy suggests the presence of short-range spin correlations. We, therefore, propose neutron diffraction measurements at sub-Kelvin temperatures to probe the nature of the ordered magnetic ground state, i.e. commensurate or incommensurate. The proposed study will enable us to extract the relevant order parameter, correlation length, and critical exponents essential to establish a universality class in this novel frustrated antiferromagnet.