| We have investigated the magnetic properties of Fe_Mn_xC_y alloys by using a combination of ab initio calculations and Monte Carlo simulations. The latter give insight into finite temperature magnetism and offer the possibility to determine the critical temperature of magnetic phase transitions. We restrict the investigation to ordered systems with 25, 50 and 75 manganese and study the influence of carbon. The combination of ab initio calculations with Monte Carlo simulations turns out to be a powerful tool to determine magnetic structures, which originate from competing ferro- and antiferromagnetic interactions in the FeMn alloys. |
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