First-principles study of electronic structure and magnetic properties of L10­-ordered FeNi, FePd, and FePt alloys

Using the first-principles method, we study the structural, electronic, and magnetic properties of three different spin configurations of the L1₀ phase of FeM alloys (M=Ni, Pd, or Pt). The calculations have been investigated using Density Functional Theory (DFT) and using several exchange-correlation functional. It is found that the PBE has the most accurate results for lattice parameters comparing with experimental values. Also, in FeM (M=Ni, Pd, or Pt) alloys, the most stable is the Ferromagnetic (FM) configuration with all spin directions aligned perpendicular to the (001) plane. Our calculations indicate that an antiferromagnetic (AFM) state can be achieved in FeM (M=Ni, Pd, or Pt) by a small variation in tetragonality ratio c/a (from 0.98 to 0.92). In AFM model, a pseudogap is observed just below fermi energy for each alloy. Our calculations show large magnetocrystalline anisotropies for FePt in the order of 3 meV/f.u. FePd and FeNi show a somewhat lower value in the range of 0.1 to 0.4 meV/f.u. Furthermore, Heisenberg exchanges interactions are calculated from first principles and Green's functions formalism.