Detail measurement on non-Kitaev term spin dynamics in -RuCl

Nakajima, Kenji   ; Kojima, Yuki*; Kurita, Nubuyuki*; Tanaka, Hidekazu*

Kitaev model is an exactly solvable model which has a quantum spin liquid state as the ground state. In Kitaev model, S=1/2 spins arranged on a honeycomb lattice are connected via three non-equivalent bonds with Ising-type interactions. -RuCl has been considered to be an excellent candidate of a Kitaev material. On the other hand, as a real material, the system has deviations from the ideal Kitaev model. The interaction between spins has non-Kitaev (Heisenberg) term as well as Kitaev one, which makes the exact ground state of -RuCl rather difficult to understand. We have studied spin dynamics in -RuCl by means of neutron scattering technique especially in low temperature and relatively lower energy range to obtained the detail picture of the ground state spin dynamics in this system, in which the non-Kitaev term highly contributes. Detail of our results and analysis will be shown in our presentation.