Monte Carlo simulations of the ABC-Stacked kagome spin structure of XY and Heisenberg models

For many years, Ir-Mn alloys have been widely used by the magnetic storage industry in thin-film form as the antiferromagnetic pinning layer in GMR (Giant Magneto Resistance) and TMR (Tunnel Magneto Resistance) spin valves. Despite the technological importance of this structure, it has not previously been noted that the magnetic Mn-ions of fcc IrMn 3 reside on Kagome layers ABC stacked along axes normal to the film plane. Results of Monte Carlo simulations will be reported on the bulk fcc Kagome lattice for both XY and Heisenberg models including the eight NN exchange interactions. Degeneracies persist in the 3D case and there is strong evidence for a fluctuation-driven first-order transition to well-defined long-range order characterized as the layered q=0 120-degree spin structure. Effects of varying the inter-layer coupling are also examined