Deconfined quantum criticality in SU(3) antiferromagnets on the triangular lattice

Abstract

We propose field theories for a deconfined quantum critical point in $SU(3)$ antiferromagnets on the triangular lattice. In particular we consider the continuous transition between a magnetic, three- sublattice color-ordered phase and a trimerized $SU(3)$ singlet phase. Starting from the magnetically ordered state we derive a critical theory in terms of fractional bosonic degrees of freedom, in close analogy to the well-developed description of the $SU(2)$ Neel - valence bond solid (VBS) transition on the square lattice. Our critical theory consists of three coupled $CP^2$ models and we study its fixed point structure using a functional renormalization group approach in a suitable large $N$ limit. We find a stable critical fixed point and estimate its critical exponents, thereby providing an example of deconfined criticality beyond the universality class of the $CP^N$ model. In addition we present a complementary route towards the critical field theory by studying topological defects of the trimerized $SU(3)$ singlet phase.