Ab initio study of FeRh alloy properties

Abstract

In this work the structural, energetic, thermodynamic, magnetic and thermoelectric properties of FeRh alloy have been studied using first-principles calculations. The structural and magnetic results obtained for the FM phase are in agreement with experimental and other theoretical calculated values (local magnetization of about 3 μB and 1 μB for Fe and Rh atoms respectively). The transition AFM to the FM state is accompanied by a 2.4% increase in the volume of the cell and by 9.6% in the Fe spin magnetic moment. The characterization of the AFM phase shows a distortion of the cubic and tetragonal cell to the orthorhombic solving the instabilities observed in the phonon band structures curves of the corresponding to cubic structure. The stability of the AFM configurations was corroborated with molecular dynamics (MD) simulations. The magnitude of the Seebeck coefficient increases with the temperature at a certain chemical potential. While the magnitude of the electrical conductivity does not present meaningful changes with the temperature in the selected values, the thermal conductivity increases with the temperature. Another consequence of the AFM to FM transition is the drop of the resistivity ρ in the FM phase as compared to the AFM state. Based on the results obtained using MD simulations from stable AFM configurations and the results of entropy changes, the configuration AFM-B (type I) could be identified as the most favorable in achieving the metamagnetic phase transition.