Antiferromagnetic to weak ferromagnetic transition and the temperature dependence of the transverse susceptibility in hematite below the Morin transition

Abstract

The antiferromagnetic (AF) to weak ferromagnetic (WF) transition in hematite below the Morin transition induced by applied magnetic field in the basal plane, was studied experimentally and theoretically. Assuming that the single ion anistropy is given by Ksin 2 θ the transition was found to occur by a gradual rotation of the AF axis, from the trigonal axis to the basal plane. This behaviour explains the reported increase of the perpendicular susceptibility with increasing temperature below the Morin transition point.