Self-reversal of Remanent Magnetization of Magnetite at Low Temperatures

Abstract

THE intensity of isothermal remanent magnetization of a ferromagnetic body usually increases with its cooling in non-magnetic space, owing to increase in spontaneous magnetization. We have found, however, that the direction of isothermal remanent magnetization of a single crystal of magnetite produced at room temperature is reversed at about −143° C in a cooling process in non-magnetic space. The sample examined by us was a single crystal of magnetite collected from Mituisi, Japan. The chemical composition (less than 0.3 per cent titanium dioxide content) and the X-ray data (a = 8.391 A) of this sample indicate that it is nearly stoichiometric magnetite.