Charge order and three-site distortions in the Verwey structure of magnetite

  title={Charge order and three-site distortions in the Verwey structure of magnetite},
  author={Mark S. Senn and Jon P. Wright and John Paul Attfield},
The mineral magnetite (Fe3O4) undergoes a complex structural distortion and becomes electrically insulating at temperatures less than 125 kelvin. Verwey proposed in 1939 that this transition is driven by a charge ordering of Fe2+ and Fe3+ ions, but the ground state of the low-temperature phase has remained contentious because twinning of crystal domains hampers diffraction studies of the structure. Recent powder diffraction refinements and resonant X-ray studies have led to proposals of a… 
The Verwey structure of a natural magnetite.
Low temperature crystal structure of a natural magnetite from a mineral sample has been determined using the same microcrystal synchrotron X-ray diffraction method and structure refinement demonstrates that the natural sample has the same complex electronic order as pure synthetic magnetite.
Charge-ordering transition in iron oxide Fe4O5 involving competing dimer and trimer formation.
This work investigates a recently discovered Fe4O5 that adopts an orthorhombic CaFe3O5-type crystal structure that features linear chains of Fe ions and discusses possible mechanisms of this transition and compares it with the trimeronic charge ordering observed in magnetite below the Verwey transition temperature.
The verwey phase of magnetite — a long-running mystery in magnetism
Magnetite (Fe3O4) is the original magnetic material and the parent of ferrite magnets, with modern applications ranging from spintronics to MRI contrast agents. At ambient temperatures magnetite has
Charge disproportionation and site-selective local magnetic moments in the post-perovskite-type Fe2O3 under ultra-high pressures
The archetypal 3d Mott insulator hematite, Fe2O3, is one of the basic oxide components playing an important role in mineralogy of Earth’s lower mantle. Its high pressure–temperature behavior, such as
Pressure tuning of charge ordering in iron oxide
The measurement of the low-temperature high-pressure phase diagram of a related material (Fe4O5) elucidates the interplay of average oxidation state and charge-ordering phenomena in the iron oxide family and proposes that theaverage oxidation state of the iron cations can pre-determine a charge- ordering pattern.
Charge orbital and spin ordering transitions in La1-Sr MnO3+δ (x = 0.67 & 0.71)
Atomic-scale structure and properties of highly stable antiphase boundary defects in Fe3O4
It is demonstrated that APB defects on the {110} planes are unusually stable and induce antiferromagnetic coupling between adjacent domains providing an explanation for the magnetoresistance and reduced spin polarization often observed.
Charge and orbital order in frustrated Pb3Mn7O15.
  • S. Kimber
  • Materials Science
    Journal of physics. Condensed matter : an Institute of Physics journal
  • 2012
Large shifts of oxygen positions are detected, which show that the interlayer sites and those which occupy voids in the kagome lattice are trivially charge ordered in both phases.
Ferroelectric order associated with ordered occupancy at the octahedral site of the inverse spinel structure of multiferroic NiFe2O4
We report a ferroelectric order at ~ 98 K for NiFe2O4, which carries an inverse spinel structure with a centrosymmetric Fd3m structure at room temperature. The value of spontaneous electric
Jahn-Teller distortion driven magnetic polarons in magnetite
Using resonant inelastic X-ray scattering over a wide temperature range across the Verwey transition to identify and separate out the magnetic excitations derived from nominal Fe2+ and Fe3+ states, which are distinct from optical excitations and are best explained as magnetic polarons.


Charge ordered structure of magnetite Fe 3 O 4 below the Verwey transition
The crystal structure of highly stoichiometric magnetite (Fe 3 O 4 ) below the Verwey transition has been refined from high-resolution neutron and synchrotron x-ray powder-diffraction data. The
Structural transformation in magnetite below the Verwey transition
The magnetite structure was studied with synchrotron x-ray powder diffraction above and below the Verwey transition. A symmetry-mode analysis was performed to obtain the atomic displacements from the
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
Low-temperature structure of magnetite studied using resonant x-ray scattering
We propose a model for the Fe atomic displacements in the low-temperature phase of magnetite Fe3O4 , based on the analysis of the photon energy dependence of the scattered intensity of selected
Ferroelectricity from iron valence ordering in the charge-frustrated system LuFe2O4
Experimental evidence for ferroelectricity arising from electron correlations in the triangular mixed valence oxide, LuFe2O4 is reported, and resonant X-ray scattering measurements are used to determine the ordering of the Fe2+ and Fe3+ ions.
Full polarization analysis of resonant superlattice and forbidden x-ray reflections in magnetite.
Through simulation of the resonant spectra it is confirmed that a degree of charge ordering takes place, while the anisotropic tensor of susceptibility scattering is responsible for the superlattice reflections below the Verwey transition.
Charge and orbital correlations at and above the Verwey phase transition in magnetite.
The subtle interplay among electronic degrees of freedom (charge and orbital orderings), spin and lattice distortion that conspire at the Verwey transition in magnetite (Fe3O4) is still a matter of
Resonant x-ray diffraction study of the charge ordering in magnetite
Powder x-ray diffraction patterns of magnetite (Fe3O4) have been recorded at 90 K, below the Verwey transition, at three wavelengths in the pre- to mid-edge region of the 7.1 keV Fe K absorption.
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, and finds an associated t(2g) orbital ordering on the octahedral Fe2+ sublattice.
Aspects of the Verwey transition in magnetite
A mechanism of the Verwey transition in magnetite $({\mathrm{Fe}}_{3}{\mathrm{O}}_{4}),$ which has been argued to be a charge ordering transition so far, is proposed. Based on mean-field calculations