Temperature and Field Dependence of Magnetization of Amorphous (Fe, Mn)-P-C Alloys

Abstract

Amorphous quasibinary alloys having the composition (Fe1−xMnx)0.75P0.15C0.10, where 0.0≤x≤1.0, were synthesized by rapid quenching from the liquid state. Their magnetic behavior was characterized by measurements of the magnetization as a function of temperature in the range 4.2°–300°K, and in fields ranging from 1 to 8.5 kOe. The iron-rich alloys with 0.0≤x≤0.4 are ferromagnetic: the magnetic moment at 0°K decreases linearly from 2.07 μB/Fe atom in Fe0.75P0.15C0.10 to 0.22 μB/(Fe, Mn) atom in (Fe0.6-Mn0.4)0.75P0.15C0.10. Judging from the large values of the parameter qc/qs, where qc and qs are the number per mole of magnetic carriers in the paramagnetic and ferromagnetic states, respectively, and also from the nonsaturating behavior of magnetization with field at 4.2°K, it appears that the ferromagnetism in these alloys may be of the itinerant kind. Alloys having 0.5≤x≤1.0 possess considerably more complex magnetic structures. They are characterized by a peak in the magnetization curve at temperatures between 15° and 40°K, and a ferrimagnetic-type curvature in the Curie-Weiss plots. This kind of magnetic behavior may be ascribed to ferrimagnetism existing in conjunction with parastic antiferromagnetism over some local regions in the amorphous structure.