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

Abstract

Amorphous quasibinary alloys having the composition (Fe_1−xMn_x)_0.75P_0.15C_0.10, 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 Fe_0.75P_0.15C_0.10 to 0.22 _μB/(Fe, Mn) atom in (Fe_0.6‐Mn_0.4)_0.75P_0.15C_0.10. Judging from the large values of the parameter q_c/q_s, where q_c and q_s 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.