Exchange interactions in barium hexaferrite -: art. no. 184433

The electronic structure of BaFe12O19 hexaferrite is calculated using the density functional theory and generalized gradient approximation (GGA). The GGA+U method is used to improve the description of strongly correlated 3d electrons of Fe. The calculation is performed for a number of spin configurations. From differences of the total energies 13 independent exchange integrals are determined as functions of the parameter U. Their magnitude decreases with increasing U, pointing to the dominating role played by the antiferromagnetic superexchange. The Curie temperature T-C is calculated using the molecular field and the random phase approximations. T-C determined by the random phase approximation agrees with the experimental T-C for U approximate to 6-7 eV.