Critical behavior of two-dimensional frustrated spin models with noncollinear order

We study the critical behavior of frustrated spin models with noncollinear order in two dimensions, including antiferromagnets on a triangular lattice and fully frustrated antiferromagnets. For this purpose we consider the corresponding O(N) x O(2) Landau-Ginzburg-Wilson (LGW) Hamiltonian and compute the field-theoretic expansion to four loops and determine its large-order behavior. We show the existence of a stable fixed point for the physically relevant cases of two- and three-component spin models. We also give a prediction for the critical exponent eta which is eta = 0.24(6) and eta = 0.29(5) for N = 3 and 2, respectively.