Effective dimer model and RVB spin liquid phase in Mott insulators with enlarged local Hilbert space

The resonating valence bond (RVB) phase is a topological spin liquid state proposed by Anderson half a decade ago as a candidate for the ground state of the spin-1/2 Heisenberg model on the triangular lattice. While extensive numerical studies showed that the ground state of the spin-1/2 model is in fact magnetically ordered, the search for a system that would realize the RVB state continues.
We consider a generalization of the triangular lattice antiferromagnet (AFM) to systems with an enlarged local Hilbert space originating from the electrons’ spin and orbital degrees of freedom. It has been previously shown that at half-filling and in presence of enhanced SU(4) symmetry these systems have an effective low energy description in terms of a quantum dimer model. In this work, we study the effective dimer model obtained from the bilinear-biquadratic SU(4) AFM. Caryring out an extensive numerical analysis using the Green’s function quantum monte carlo method, we find strong evidence for the presence of the topological RVB spin liquid state in a finite range of biquadratic couplings.