Antiferromagnetism in $\gamma$-phase manganese-palladium and manganese-nickel alloys

Abstract

Manganese-rich γ-phase alloys of manganese-palladium and manganese-nickel have been investigated with x-ray and neutron diffraction, and the Néel and structure-transformation temperatures fixed with the aid of Young's modulus, resistivity and susceptibility measurements. High manganese content alloys distort from a face-centred cubic to a face-centred tetragonal structure at the Néel temperature. Alloys containing more than 12 at.% Pd and 15 at.% Ni are cubic below the Néel temperature (1 gt-or-equal, slanted c/a greater-than sign R: 0.999), and do not distort till a much lower temperature. In the more solute-rich alloys the structure transformation is suppressed entirely. A mechanism for the distortion is suggested, and it is pointed out that the resistivity and susceptibility results are not consistent with a localized model of the d electrons in these alloys.