The Kitaev model is an exactly solvable quantum-spin-liquid model defined on a honeycomb lattice with S = 1/2. The key element underlying this model is the bond-anisotropic Kitaev interaction. However, in a spin-only system, it is unrealistic to have such anisotropic interactions. In this talk, the speaker will show that the Kitaev interaction can be realized in a Mott insulator α-RuCl3, which has an effective spin of 1/2 by entangling the spin and orbital degrees of freedom. I will also show that by applying an in-plane magnetic field, the zigzag magnetic order ground state in α-RuCl3 can be completely suppressed, and a quantum-spin-liquid state can be induced. More recently, we extend the Kitaev physics to higher-spin system, where we find in a honeycomb-lattice antiferromagnet Na3Ni2BiO6 that there is a profound 1/3 magnetization plateau, which is stabilized by the Kitaev interaction, as evidenced from the neutron spectroscopy. This will also be discussed in the presentation.
HK Institute of Quantum Science & Technology,
Room525, Chong Yuet Ming Physics Building, The University of Hong Kong
Phone: 3917 1108