Electronic structure of magnetite at low temperature

Recent progress in NMR analysis of Fe₃O₄ has revealed the presence of five B site Fe³⁺ ions, called B-1, B-2, B-4 and B-5. From the symmetry of the NMR lines of these ions, a very new electron ordering was proposed, in which Fe³⁺-I ions make pairs along [11̄0] direction and Fe²⁺-II ions also behave in the same way. In this Mizoguchi's model, all the (001) planes in which B sites align along [11̄0] are composed of these pairs exclusively with two kinds of pairs aligning alternately. The other (001) planes in which B sites align along [011] are composed of Fe³⁺-II and Fe²⁺-I ions, which align as 3·1·3··· and 1·3·1· ··. The significance of this model in contrast to Iida's model in which all (001) planes have the same alternative sequence of Fe³⁺ and Fe²⁺ ions is discussed, concluding that, although the new model is quite promising, the NMR study at the present stage still cannot eliminate the latter model.