Exchange constants and transfer integrals of spinel ferrites

P. G. BERCOFF; H. R. BERTORELLO

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

Elsevier

Lugar: Amsterdam; Año: 1997 vol. 169 p. 314 - 322

0304-8853

We have studied Fe3 O4, Co Fe2 O4, Ni Fe2 O4 and Cu Fe2 O4 considering Néel´s two-sublattice collinear model and the superexchange theory. We have found that - for this theory to be valid - the interaction between ions in tetrahedral sites should be very weak, and we have proposed a model to find the constants JAB  and JBB  with the assumption that JAA = 0.   Using this model, the calculated values of these constants follow the expected tendencies for the four systems under study, as well as the ion-to-ion constants of Anderson´s theory which we obtained through the assessment of the transfer integrals.