A spin­-orbit coupled triangular lattice quantum spin liquid in YbMgGaO4: a semiclassical study

Recently YbMgGaO4 is proposed to be the first strong spin­-orbit coupled quantum spin liquid candidate system that contains odd number of electron per unit cell with effective spin­ 1/2 local moments. In this talk we analyze the classical phase diagram of the most generic model that describes the Yb effective spin ­1/2 local moments on the triangular lattice. We show the frustration is strong near the phase boundary between the 120­ degree state and the stripe ordered phase. Further, we study the quantum fluctuation of the spin momentum by the linear spin wave theory and find that the magnetic order is destroyed in the strongly frustrated regimes of the phase diagram. Our result is compatible with the experimental results that suggest a quantum spin liquid ground state.