Monte Carlo simulations of magnetic ordering in the fcc Kagome lattice

Monte Carlo simulation results are reported on magnetic ordering in ABC stacked Kagom\'{e} layers with fcc symmetry for both XY and Heisenberg models which include exchange interactions with the eight near-neighbors. Well known degeneracies of the 2D system persist in the 3D case and analysis of the numerical data provides 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. The results are relevant to understanding the role of frustration in IrMn$_3$ alloys widely used by the magnetic storage industry as thin-films in the antiferromagnetic pinning layer in GMR and TMR spin valves. Despite the technological importance of this structure, it has not previously been noted that the magnetic Mn-ions of fcc IrMn$_3$ form Kagom\'{e} layers.