A Short Range Order Effect in Antiferromagnetics

抄録

A statistical theory of antiferromagnetism, which is an extension of Nakamura’s and Kasteleijn and Kranendonk’s theory, is developed. Our theory reasonably well explains the unusual behaviors of paramagnetic susceptibilities of CuF₂·2H₂O and CuCl₂·2H₂O. The theory is compared with experiments, and the following information is obtained. In the case of CuF₂·2H₂O, the ferromagnetic exchange coupling constant is smaller than about 1/3 of the antiferromagnetic exchange coupling constant. The ratio of these two exchange coupling constants in CuCl₂·2H₂O is about 0.55, which differs from 0.3 proposed by Oguchi and 0.165 by Marshall.