title: Ising transition driven by frustration in a 2D classical model with continuous symmetry.
abstract: We study the thermal properties of the classical antiferromagnetic Heisenberg model with both nearest (J1) and next-nearest (J2) exchange couplings on the square lattice by extensive Monte Carlo simulations. We show that, for J2/J1>1/2, thermal fluctuations give rise to an effective Z2 symmetry leading to a finite-temperature phase transition. We provide strong numerical evidence that this transition is in the 2D Ising universality class, and that T(c)-->0 with an infinite slope when J2/J1-->1/2.
authors: Institut de Physique Théorique, Université de Lausanne, CH-1015 Lausanne, Switzerland.
authors: Cédric
authors: C
authors: Weber
authors: Luca
authors: L
authors: Capriotti
authors: Grégoire
authors: G
authors: Misguich
authors: Federico
authors: F
authors: Becca
authors: Maged
authors: M
authors: Elhajal
authors: Frédéric
authors: F
authors: Mila