Magnetism in Perovskites

Perovskites Structure-Property Relationships, First Edition. Richard J. D. Tilley. 2016 John Wiley Sons, Ltd. Published 2016 by John Wiley Sons, Ltd. 

An important aspect of superexchange is the fact that no actual electron transfer takes place. Superexchange is therefore possible between cations in both octahedral and tetrahedral sites and between cations in other coordination polyhedra, such as square pyramidal. This means that antiferromagnetic ordering can take place in brownmillerites or other perovskites in which the octahedral coordination polyhedron has been significantly changed. (This is not so with interactions in which electron exchange actually occurs.) 

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