Half-Metallic Ferrimagnetism in the MnNbAl Full-Heusler Compound: a First-Principles Study.

A first-principles study of the electronic structure and magnetic properties of the Heusler compound Mn NbAl has been performed. The calculations have been performed by using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method. It is found that the AlCu Mn-type structure is preferable energy wise than the CuHg Ti-type structure and exhibits half-metallic ferrimagnetism. The calculated total magnetic moment of Mn NbAl is 2 μ at the equilibrium lattice constant of 6.005 Å for the AlCu Mn-type structure. The total spin magnetic moment obeys the Slater-Pauling rule and is based on mainly the Mn atoms. The spin-down electrons are metallic, but the spin-up bands are semiconductor with a gap of 0.37 eV, and the spin-flip gap is of 0.09 eV. The AlCu Mn-type Mn NbAl full-Heusler compound keeps 100 % of spin polarization for lattice constants ranging between 5.93 and 6.20 Å. The Curie temperature is estimated to be 994 K in the mean field approximation (MFA). [ABSTRACT FROM AUTHOR]