The Change of Spontaneous Magnetization with Hydrostatic Pressure

Abstract

Measurements have been made of the effect of pressure on the spontaneous magnetization of nickel, cobalt, and a series of nickel alloys. The measurements were made using a thin-disc permeameter designed to produce high magnetic fields for only a very small power consumption. The results are in good general agreement with the results of other hydrostatic pressure experiments and with the results of experiments on the thermodynamically related `forced' volume magnetostriction. An adequate verification of the important thermodynamic relation (partial differentialV / partial differentialH)pT = - (partial differentialM / partial differentialp)H,T has been obtained for the nickel-iron alloy system. The results do not agree with the anomalous results reported by Stacey who used Bridgman's thin-disc technique of generating high pressures. Under some conditions nickel shows an anomalously large, linear, decrease of spontaneous magnetization with pressure; possible reasons for this are discussed.