First-Principles Study of Half-Metallic and Magnetic Properties for the Heusler Alloys Fe2CrX (X = P, As, Sb, Bi)

The electronic structure and magnetism of the Heusler alloys Fe2CrX (X = P, As, Sb, Bi) have been investigated by first-principles calculations based on density functional theory. The calculations show that all Fe2CrX alloys are half-metals with a magnetic moment of 3.00 μB at their respective equilibrium lattice constants, which is in good agreement with the Slater–Pauling rule. The origin of energy gap in the minority-spin states is discussed in terms of the hybridization among the 3d electrons of the Fe and Cr atoms. The total magnetic moments for these alloys are mainly determined by the partial moment of Cr atom. The change of Fe and Cr moments compensates each other and keeps the total magnetic moment as an integer when the X atom changes By investigating the effects of lattice constants on half-metallic and magnetic properties of Fe2CrX alloys, it is found that half-metallic properties of Fe2CrSb and Fe2CrBi alloys are the most insensitive to the lattice distortion and a 100 % spin polarization can be obtained when the lattice is expanded from −9 % to + 3 %.