Monte Carlo Simulations of Frustrated Classical Spin Systems

Abstract

We present preliminary results of Monte Carlo simulations of classical bilayer Heisenberg models with frustrating interlayer couplings. We studied the low temperature magnetic structure of three geometrically different systems. In systems with identical square lattices in the two layers, we can reproduce the basic features of the ground state phase diagram of the classical J ₁ — J ₂ model if the relative displacement of two layers is along a diagonal; when the two layers are off-set by half a lattice constant in only one direction, we find that a twisted spin phase can be set up in the direction of frustration. We also studied a system with two different square lattices arranged to resemble the geometry found in the mixed layer pnictide oxides (Sr ₂ Mn ₃ Pn ₂ O ₂, Pn = As, Sb) of Brock et al. Within a restricted region of phase space, this model does exhibit the orthogonal order observed in experiments.