Abstract
We present the results of our Monte Carlo simulation of the Ising-O(3) model on two-dimensional (2D) and quasi-2D lattices. This model is an effective classical model for the stacked square-lattice - Heisenberg model, where the nearest-neighbor () and next-nearest-neighbor () couplings are frustrated and we assume that is dominant. We find an Ising ordered phase in which the O(3) spins remain disordered in a moderate quasi-2D region. There is a single first-order transition for a sufficiently large 3D coupling, in agreement with a renormalization group treatment. The subtle region in which the single transition splits into two transitions is also discussed and compared against recent measurements of two very close transitions in BaFeAs. Our results can provide a qualitative explanation of the experiments on ferropnictides, namely the observed sequence and orders of the structural and magnetic transitions, in terms of the ratio between the interlayer and intralayer coupling.
4 More- Received 7 August 2011
DOI:https://doi.org/10.1103/PhysRevB.84.214429
©2011 American Physical Society