First-principles investigation of L10-disorder phase equilibrium in Fe-Pt system

First-principles study is attempted to investigate L10-disorder phase equilibrium in Fe-Pt system. The present study consists of electronic structure total energy calculations by FLAPW for the ground state and statistical mechanics calculations by Cluster Variation Method for finite temperatures. It is revealed that the magnetism plays a crucial role in the phase stability. The spin polarized FLAPW calculation confirms that the most stable magnetic state for FePt3 (L12) is anti-ferro, and the incorporation of anti-ferro magnetic state is critical to reproduce the experimental L10-disorder transition temperature. Thermal vibration effects considered based on Debye-Gruneisen model further improve the calculated transition temperature.