Magnetization of Iron-Nickel Alloys Under Hydrostatic Pressure

TLDR

Recent low‑temperature pressure studies by Kondorsky and Sedov confirm that compression reduces magnetization in Fe‑Ni alloys. The authors measured magnetization of Fe, Ni, and Fe‑Ni alloys under hydrostatic pressures up to 3000 atm and magnetic fields up to 12 kOe. Compression rapidly decreases the saturation moment and Curie temperature of fcc Fe‑Ni alloys, especially near 30 % Ni, while increasing Fe content further lowers both; a partial bcc transformation restores higher values but reduces pressure sensitivity, indicating coexistence of ferromagnetic and antiferromagnetic order in these alloys.

Abstract

Magnetization measurements were made on iron, nickel, and their alloys in hydrostatic pressures up to 3000 atm and in fields up to 12 000 oe. The results of these room-temperature measurements, combined with Patrick's results on the pressure dependence of the Curie temperatures, indicate that σ0, the saturation moment at 0°K, as well as θ, the Curie temperature, is rapidly decreased by compression in the fcc alloys of about 30% Ni. This is in agreement with the recent low-temperature pressure measurements of Kondorsky and Sedov. For these alloys, both σ0 and θ are decreasing with increasing Fe concentration. When the 30% Ni alloy is partially transformed to bcc, its σ0 and θ rise to much higher values but its magnetization is much less pressure dependent. It is concluded that unlike the more simple ferromagnetic bcc alloys, the fcc Fe-Ni alloys have a coexistence of ferromagnetic and antiferromagnetic order, similar to that recently proposed for the Ni-Mn alloys.