Theory of Magnetism in FeCl₂·2H₂O

Abstract

Crystal field theory developed by Abragam and Pryce is used to formulate the anisotropic exchange interactions in FeCl₂·2H₂O. This crystal is antiferromagnetic in which Fe⁺⁺ ions form ferromagnetic linear chains coupling antiferromagnetically to adjacent chains similar to CO⁺⁺ ions in CoCl₂·2H₂O and CoBr₂·2H₂O. There are the similar two abrupt jumps in the high-field magnetization to those in CoCl₂·2H₂O and CoBr₂·2H₂O. The numerical values of exchange integrals are estimated. By the use of these values the above magnetization process can be explained. It is predicted that Schottky anomaly in the specific heat may be detected at about 6.4°K.