Ferrimagnetic ferroelectricity of Fe3O4

Magnetite (Fe3O4): a new variant of relaxor multiferroic?

“…The ferroelectric polarization detected in magnetite films [34] and single crystals [27,30,46] can be understood in the following scenario. The ferroelectric phase appears at the Verwey transition in the non-centrosymmetric monoclinic Cc symmetry.…”

Magnetoelectric Coupling Effects in Multiferroic Complex Oxide Composite Structures

“…In particular, it is a ferrimagnetic conductor with a Curie temperature T C ≈ 850 K108 and exhibits a structural transition with decreasing temperature from the cubic inverse spinel to an orthorhombic structure at 123 K, which is accompanied by an increase in resistivity by more than a factor of 100, which is called the Verwey transition,109, 110 akin to a metal‐insulator (Mott) transition 111. In the orthorhombic phase, Fe 3 O 4 is both ferrimagnetic and ferroelectric,112–116 and is hence a single‐phase multiferroic.…”

Pyroelectric detection of spontaneous polarization in magnetite thin films

“…32 It is clear that in such materials there is a relationship between the pattern of charge ordering and polarization. However, there is still a discrepancy in the Fe 3 O 4 experimental results, since spontaneous polarization has only been observed well below the Verwey transition point, [9][10][11][12][13][14][15][16][17][18] while x-ray and neutron diffraction studies suggest that the charge-ordered state responsible for the ferroelectricity appears at the Verwey transition and is unchanged upon further cooling. 24,26,28,29 One possible reason for this discrepancy is the high leakage current of Fe 3 O 4 crystals just below the charge-ordering temperature of 120 K.…”