SATURATION MOMENTS OF MIXED FERRITES - A SIMPLE THEORY

The substitution dependence of the magnetic moment at 0°K [M (0, x)] of the ferrimagnetic system (ZnxFe1-x) [Me 1-xFe1+x]O4 (Me stands for Mn, Co, or Ni) is calculated using a simple statistical local-molecular-field model. The model is able to reproduce quantitatively the experimental results for M (0, x) in the range 0.0≤x<0.7. The model has no continuously adjustable parameters but assumptions are made on the relative strength of A-B and B-B pair exchange interactions. Very good agreement with experimental observations is obtained if the following assumptions are made. For Mn and Fe in the B site, the antiferromagnetic A-B exchange JAB is more than six times larger than the average antiferromagnetic B-B exchange J̄BB. For Co, the inequality 3J̄BB<JAB<6J̄BB holds, and for Ni, the inequality 2J̄BB<J AB<3J̄BB holds. © 1969 The American Institute of Physics.