Magnetic properties of theFe0.65(Ni1−xCox)0.35andFe0.65(Ni1−yMny)0.35alloy systems

Abstract

The magnetization, Curie temperature, and pressure dependence of the Curie temperature have been measured for the ${\mathrm{Fe}}_{0.65}{({\mathrm{Ni}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x})}_{0.35}$ alloy system, where $0\ensuremath{\le}x\ensuremath{\le}0.08$. The magnetization and Curie temperature were observed to be nearly independent of Co concentration, while the pressure derivative of the Curie temperature was found to increase in magnitude with increasing Co concentration. These results are to be compared with previous measurements on the ${\mathrm{Fe}}_{0.65}{({\mathrm{Ni}}_{1\ensuremath{-}y}{\mathrm{Mn}}_{y})}_{0.35}$ alloy system, where the magnetization and Curie temperature decrease with increasing Mn concentration. The pressure derivatives of the Curie temperatures for both alloy systems have similar dependences on composition. The behavior of both alloy systems is compared and discussed in terms of the modified Zener model, which allows both localized and itinerant magnetic electrons. The expected trends in the Coulomb repulsive energy for itinerant electrons of opposite spin on the same site as well as the average number of itinerant electrons per site for the various constituent atoms qualitatively explain the observed differences between the two alloy systems.