Vanishing Fe 3d orbital moments in single-crystalline magnetite

Goering, E.; Gold, Steven D.; Lafkioti, Myrsini; Schütz, Gisela

doi:10.1209/epl/i2005-10359-8

Cited by 86 publications

(138 citation statements)

References 41 publications

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“…3(d) (top curve). The spectrum provides further support that the crystal is magnetite, 39 which has a significant XMCD signal [40][41][42] at the shoulder before the maximum of the L 3 XAS spectra. Taking images at this photon energy (705.8 eV) with different helicities and subtracting them pixel by pixel gives the XMCD images of Fig.…”

mentioning

confidence: 63%

“…The XMCD difference spectrum [ Fig. 3(d), bottom curve] shows a well-defined peak structure at the L 3 and L 2 edges that is characteristic of magnetite 42 (the inset shows the XMCD difference spectrum from stoichiometric magnetite). The two negative peaks at the L 3 edge originate mostly from the iron cations sitting at the octahedral sites, with nominal valences +2 and +3.…”

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confidence: 99%

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Magnetism in nanometer-thick magnetite

et al. 2012

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The oldest known magnetic material, magnetite, is of current interest for use in spintronics as a thin film. An open question is how thin can magnetite films be and still retain the robust ferrimagnetism required for many applications. We have grown 1-nm-thick magnetite crystals and characterized them in situ by electron and photoelectron microscopies including selected-area x-ray circular dichroism. Well-defined magnetic patterns are observed in individual nanocrystals up to at least 520 K, establishing the retention of ferrimagnetism in magnetite two unit cells thick.

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confidence: 63%

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Magnetism in nanometer-thick magnetite

et al. 2012

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“…71 In addition, the unquenched Fe B orbital moment was also reported to be confirmed by the LDA+U calculations. Later, however, this experimental finding was questioned by Goering et al 72 The average orbital moments between −0.001 µ B and 0.06 µ B…”

Section: Orbital Orderingmentioning

confidence: 96%

Electronic structure of charge-orderedFe3O4from calculated optical, magneto-optical Kerr effect, and OK-edge x-ray absorption spectra

et al. 2006

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The electronic structure of the low-temperature (LT) monoclinic magnetite, Fe 3 O 4 , is investigated using the local spin density approximation (LSDA) and the LSDA+U method. The selfconsistent charge ordered LSDA+U solution has a pronounced [001] charge density wave character.In addition, a minor [00 1 2 ] modulation in the phase of the charge order (CO) also occurs. While the existence of CO is evidenced by the large difference between the occupancies of the minority spin t 2g states of "2+" and "3+" Fe B cations, the total 3d charge disproportion is small, in accord with the valence-bond-sum analysis of structural data. Weak Fe orbital moments of ∼0.07µ B are obtained from relativistic calculations for the CO phase which is in good agreement with recent x-ray magnetic circular dichroism measurements. Optical, magneto-optical Kerr effect, and O Kedge x-ray absorption spectra calculated for the charge ordered LSDA+U solution are compared to corresponding LSDA spectra and to available experimental data. The reasonably good agreement between the theoretical and experimental spectra supports the relevance of the CO solution obtained for the monoclinic LT phase. The results of calculations of effective exchange coupling constants between Fe spin magnetic moments are also presented.

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“…28 and 29͒ or in a mixed ␣3d 5 + ␤3d 6 state ͑Fe 3 O 4 ͒ with intermediate value of r Ͻ 0.18. 30,31 Any mixture of the three oxide stochiometries would therefore lead to r Ͻ 0.26. For the surface adsorbed Fe atoms we obtain r = 0.53Ϯ 0.09 at = 0°and r = 0.31Ϯ 0.07 at = 70°.…”

Section: A Chemical and Magnetic Propertiesmentioning

confidence: 99%

Magnetic anisotropy of Fe and Co adatoms and Fe clusters magnetically decoupled fromNi3Al(111)by an alumina bilayer

et al. 2010

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The magnetic properties of individual Fe and Co atoms as well as of small Fe clusters adsorbed on two atomic layers of Al 2 O 3 grown on Ni 3 Al͑111͒ have been investigated by x-ray absorption spectroscopy and x-ray magnetic circular dichroism. We find ratios of the orbital over the effective spin magnetic moments of r = 0.53Ϯ 0.09 for Fe and r = 0.91Ϯ 0.06 for Co, which are both very close to the free-atom values of r = 0.5 and 1, respectively. The magnetization curves acquired at the Fe and Ni edges demonstrate a distinctly different magnetization reversal of the transition-metal nanostructures and the substrate excluding magnetic dipolar or exchange coupling through the alumina film. Our data reveal an out-of-plane easy magnetization axis for Fe and Co originating from the spatially anisotropic hybridization of the 3d states of the adatom, with the 2p states of the oxygen terminated Al 2 O 3 surface. We conclude that the alumina film effectively decouples the magnetic adatoms from the underlying metal substrate while providing a crystal-field environment giving rise to high magnetic anisotropy.

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Vanishing Fe 3d orbital moments in single-crystalline magnetite

Cited by 86 publications

References 41 publications

Magnetism in nanometer-thick magnetite

Magnetism in nanometer-thick magnetite

Electronic structure of charge-orderedFe3O4from calculated optical, magneto-optical Kerr effect, and OK-edge x-ray absorption spectra

Magnetic anisotropy of Fe and Co adatoms and Fe clusters magnetically decoupled fromNi3Al(111)by an alumina bilayer

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