(Received August 28, 1952)
In this paper the theories of superexchange interaction developed by Kramers and Anderson have been more generally reformalized by means of the well-known vector model. The formulation can also be applied to the problem of molecular structure in which a consideration of the various orbital configurations of electrons is required. From an application of this method to the crystal which contains the magnetic ions separated from each other by the negative ions, it is found that magnetic interaction (or superexchange interaction), can be written in terms of spin operators as well as the ordinary exchange interaction, as Anderson concluded previously. As far as one accepts the assumptions that interatomic exchange integrals are negative and inneratomic exchange integrals positive, it must be said that superexchange interaction is ferromagnetic if one considers only the intermediate states in which an electron on a negative ion has jumped into and unoccupied orbit of the neighbouring magnetic ion. On the other hand the superexchange interaction is antiferromagnetic if one considers only the intermediate states in which the electron has jumped into the orbit which is already occupied by an electron. Actually two sorts of these interactions will be considered to be co-existent in any magnetic compounds and the antiferromagnetic coupling seems to be predominant in most cases.
URL : http://ptp.ipap.jp/link?PTP/8/416/
DOI : 10.1143/PTP.8.416