Direct Observation oft2gOrbital Ordering in Magnetite

Comment on "Direct observation of charge ordering in magnetite using resonant multiwave x-ray diffraction".

The study of the Verwey transition in magnetite has been a matter of intense study during the last years [1,2]. The mechanism proposed by Verwey [3] was the charge localization and ordering of the electrons at the iron octahedral sites giving rise to an ordered sequence of Fe3þ and Fe2þ ions. Recent x-ray diffraction and resonant x-ray scattering at the iron K edge have strongly modified this d...

Direct observation of the thermal demagnetization of magnetic vortex structures in nonideal magnetite recorders

The thermal demagnetization of pseudo-single-domain (PSD) magnetite (Fe3O4) particles, which govern the magnetic signal in many igneous rocks, is examined using off-axis electron holography. Visualization of a vortex structure held by an individual Fe3O4 particle (~250 nm in diameter) during in situ heating is achieved through the construction and examination of magnetic-induction maps. Stepwis...

Charge-orbital ordering and Verwey transition in magnetite.

Local density approximation + Hubbard U (LDA + U) band structure calculations reveal that magnetite (Fe3O4) forms an insulating charge-orbital-ordered state below the Verwey transition temperature. The calculated charge ordering is in good agreement with that inferred from recent experiments. We found an associated t(2g) orbital ordering on the octahedral Fe2+ sublattice. Such an orbital orderi...

Charge-ordering in Magnetite studied by Magnetic Compton Scattering

Long range charge ordering in magnetite below the Verwey transition.

The crystal structure of Fe(3)O(4) below the 122 K Verwey transition has been refined using high-resolution x-ray and neutron powder diffraction data. The refinements give direct evidence for charge ordering (CO) over four independent octahedral Fe sites, two with a charge of +2.4 and the other two of +2.6. CO schemes consistent with our model do not meet the widely accepted Anderson condition ...