Monte Carlo simulations of magnetic ordering in the fcc Kagome lattice

TL;DR

This study uses Monte Carlo simulations to investigate magnetic ordering in fcc Kagome lattices, revealing a fluctuation-driven first-order transition to long-range order and implications for magnetic storage materials.

Contribution

First detailed Monte Carlo analysis of magnetic ordering in 3D fcc Kagome lattices, highlighting fluctuation-driven phase transitions and effects of inter-layer coupling.

Findings

Evidence for a fluctuation-driven first-order transition.

Persistence of 2D degeneracies in 3D systems.

Relevance to magnetic storage alloys like IrMn$_3$.

Abstract

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.