Abstract
Lattice U(1) instantons in 2+1 dimensions have no fermion zero modes and do not break U(2n) flavor symmetry. Nevertheless, instantons in the presence of massless fermions interact via logarithmic potentials. These results are applied to the ‘‘flux’’ phase of a SU(n) antiferromagnet and the possibility of a transition from a gapless spin-liquid state to Néel order as n decreases from 4 to 2 is discussed.