Novel local symmetries and chiral-symmetry-broken phases in S=(1/2 triangular-lattice Heisenberg model

Using a non-mean-field approach the triangular lattice S=(1/2 Heisenberg antiferromagnet with nearest- and next-nearest-neighbor coupling is shown to undergo an Ising-type phase transition into a chiral symmetry broken phase (Kalmeyer-Laughlin--like state) at small T. Removal of next-nearest-neighbor coupling introduces a local Z₂ symmetry, thereby suppressing any finite-T chiral order.