The magnetic phase transition in Mn2-xFexB alloys: First-principles calculations

Based on the density-functional theory (DFT) and the generalized gradient approximation (GGA), Mn2-xFexB (0 ≤ x ≤ 2) alloys are investigated for their magnetic, electronic and structural properties by the first principles calculations with the virtual crystal approximation (VCA). Two extremes at x = 0 and 2, respectively, show that anti-ferromagnetic Mn2B and ferromagnetic Fe2B have the same electronic structure as I4/mcm but with different lattice constants. There is a critical point for phase transition from antiferromagnetic (AFM) to ferromagnetic (FM) at x = 0.5 according to calculations under the condition of the lowest energy for the four states of non-magnetic (NM), FM, AFM1 and AFM2. It is in agreement with the Stoner model in the range of the FM state.