Emergent Critical Phase and Ricci Flow in a 2D Frustrated Heisenberg   Model
  We introduce a two-dimensional frustrated Heisenberg antiferromagnet on interpenetrating honeycomb and triangular lattices. Classically the two sublattices decouple, and "order from disorder" drives them into a coplanar state. Applying Friedan's geometric approach to nonlinear sigma models, we show that the scaling of the spin-stiffnesses corresponds to the Ricci flow of a 4D metric tensor. At low temperatures, the relative phase between the spins on the two sublattices is described by a six-state clock model with an emergent critical phase. 
Peter P. Orth, Premala Chandra, Piers Coleman, J\"org Schmalian
cond-mat.str-el gr-qc hep-lat hep-th