Structural, electronic and magnetic properties of the Mn50Al46Ni4 alloy.

The structural, electronic and magnetic behavior of the as-cast and annealed Mn 50 Al 46 Ni 4 and Mn 54 Al 46 alloys was investigated. It was found that annealing at 470 °C promotes the formation of the τ phase in both alloys, however, all of the prepared samples were phase mixtures. The τ phase was found along with the κ phase (CsCl-type structure) only in the Mn 50 Al 46 Ni 4 alloy. M ( T ) curves show two transitions at 437 K and 634 K corresponding to the ferromagnetic κ and τ phases, respectively. A maximum τ phase content of 76 wt% for Mn 54 Al 46 and 74 wt% for Mn 50 Al 46 Ni 4 was found for the samples annealed at 470 °C for 6 h. Saturation magnetization values at 4 K of 112 Am 2 /Kg and 106 Am 2 /Kg were obtained for Mn 54 Al 46 and Mn 50 Al 46 Ni 4 respectively, in good agreement with the values reported in the literature. Band structure calculations show a preference for Ni to occupy the Mn 1 a and 1 c crystallographic sites, the calculated magnetic moments for Mn 54 Al 46 and Mn 50 Al 46 Ni 4 being in good agreement with the experiment. The electronic, structural and magnetic properties of these alloys are discussed as a function of composition and preparation route. [ABSTRACT FROM AUTHOR]