Estimates are made of the Weiss factors for Fe, Co, and Ni using the author's previously proposed theory of indirect coupling via the conduction electrons. In this estimate use is made of only (i) the spectroscopic data for the coupling between the spin of the outer $4s$ electron and the spin of the inner incomplete $3d$ shell for the isolated atoms, (ii) the Hartree solution for the isolated Fe atom, (iii) the assumption that the conduction electrons behave as a free electron gas, (iv) the assumption that the direct coupling between adjacent $d$ shells is negligible. The computed Weiss factors increase in the series Fe, Co, Ni in the same manner as do the empirical factors, but are somewhat larger. This discrepancy is in the right direction demanded by the previously proposed postulate that the direct interaction between adjacent $d$-shells always tends to an antiferromagnetic alignment.

• Received 12 April 1951

DOI:https://doi.org/10.1103/PhysRev.83.299