Ferromagnetic-Paramagnetic Transition in Iron

Abstract

Magnetization per gram of an iron sphere σ as a function of temperature T has been studied between the ferromagnetic Curie temperature TFC and TFC+30°K with applied magnetic fields between 180 and 1360 Oe. The temperature TFC, appearing as an abrupt decrease in the σ vs T curves, occurs at 1044±2°K. Mass magnetic susceptibility of iron, above the ferromagnetic Curie temperature in small magnetic fields, is proportional to (T-TFC)−4/3, which is the theoretical prediction for a Heisenberg three-dimensional ferromagnet.