‘Memory’ of Initial Remanent Magnetization and Number of Repeating of Heat Treatments in Low-temperature Behaviour of Hæmatite

Abstract

IT has recently been reported that the remanent magnetization of hæmatite (αFe₂O₃) indicates a marked thermal hysteresis phenomenon during a cooling–heating cycle to interpose the transition temperature of about 250° K., where the rotation of spin axis occurs: on cooling below 250° K. and then re-heating to room temperature, the direction of the remanent magnetization is still memorized in the specimen, although its intensity does not recover its original value before the cooling–heating cycle¹. A satisfactory explanation of such behaviour has not so far been given, though much work has been carried out on this problem^2,3. In this communication, new information on the ‘memory’ phenomenon will be reported.