A first-principles study aided with Monte Carlo simulations of carbon doped iron-manganese alloys

We have investigated the complex magnetic properties of Fe1−xMnxCy alloys by using an iterative combination of ab initio calculations and Monte Carlo simulations. The latter gives insight into finite temperature magnetism and allows 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 at octahedral interstitial sites on the magnetic properties. The combination of ab initio calculations with Monte Carlo simulations turns out to be a powerful tool to determine the complex magnetic structures, which originate from the competition of ferro- and antiferromagnetic interactions in the FeMn alloys