A linear/quadratic order parameter coupling description of the Verwey transition in magnetite, Fe3O4

Carpenter, M.A.; Harrison, R.J.; Shaw-Stewart, J.; Adachi, K.; Senn, M.S.; Howard, C.J.

doi:10.1107/S2052520625004779

Acta Crystallographica Section B
Acta Crystallographica
Section B STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS

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Figure 1
Schematic representation of cation charge ordering in octahedral sites for ordered arrangements arising from equal proportions of Δ₅ and X₁. Small and large circles represent two different formal charges. Δ₅ gives alternation in rows within the layers at z = c/8, 3c/8, 5c/8, 7c/8, but has no effect on atoms in the layers at z = 0, 2c/8, 4c/8, 6c/8 (Fig. S2). X₁ leads to alternation of layers at z = 0, 2c/8, 4c/8, 6c/8, with only small or only large circles in each, but has no effect in the layers at z = c/8, 3c/8, 5c/8, 7c/8 (Fig. S3). The ordering scheme for Δ₅ gives doubling of the c-repeat. The pattern has been laid out to show that it is the same as shown for the P2/c structure illustrated in Figure 2 of Yamauchi et al. (2009