  We show that several distinct broken-symmetry phases in a spin-1/2
anti-ferromagnet on a square lattice with easy-plane anisotropy, including
valence bond solid, chiral spin liquid, and the XY-ordered state, can all be
accessed by perturbing a multi-critical point with two massless Dirac fermions
coupled to a level-one Chern-Simons gauge field. This allows for a unified
description of these phases, as well as the phase transitions between them. In
a specific phase transition our analysis provide a lattice realization of one
of the recently proposed fermion-boson duality, thus lending support to it. We
also briefly discuss the relation between our work and the long-sought
de-confined criticality in such systems.
