Fe3O4 films on Ag(001)—Generation of high-quality epitaxial ferrimagnetic metal oxide films

Bruns, Daniel; Lindemann, S. R.; Kuepper, K.; Schemme, Tobias; Wollschläger, J.

doi:10.1063/1.4816787

Cited by 11 publications

(10 citation statements)

References 15 publications

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“…These features are characteristic of a mixed-valence Fe 2+ /Fe 3+ compound such as Fe 3 O 4 . 29,47,49,50 The presence of multiple valence states results in a large number The data therefore appear somewhat contradictory; one one hand, the STM and LEED measurements indicate a simple (1 × 1) lattice characteristic of FeO. On the other hand, experiments show that the multilayer structure forms under more oxygen-rich conditions and core level spectroscopy indicates the presence of a significanteven dominantcomponent of Fe 3+ , suggesting that the ratio of O/Fe > 1.…”

Section: ■ Resultsmentioning

confidence: 85%

Growth of Ultrathin Iron Oxide Films on Ag(100)

et al. 2015

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Ultrathin iron oxide films are useful model materials for fundamental studies of surface processes and exhibit intriguing properties as catalysts, as demonstrated recently in a number of studies utilizing platinum as a substrate. We report a study of the initial stages of iron oxide film growth on an Ag(100) surface using scanning tunneling microscopy, low energy electron diffraction, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure spectroscopy, with the goal of elucidating the effects of the substrate material on FeO x film growth and physical properties. We demonstrate that a well-ordered, monolayer-thick FeO(111) film can be prepared which is similar to the well-studied structure formed on Pt (111), though with a significantly expanded lattice constant indicative of smaller Fe−O buckling and weaker interactions with the substrate. Increased oxygen pressure during deposition leads to formation of a multilayer phase taking the form of well-ordered islands. Although superficially similar to FeO(111), spectroscopic measurements show a substantial proportion of Fe 3+ in the phase. FeO(100) grains are observed upon deposition at elevated substrate temperatures, which is proposed to result from formation and oxidation of iron clusters embedded in the surface.

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Section: ■ Resultsmentioning

confidence: 85%

Growth of Ultrathin Iron Oxide Films on Ag(100)

et al. 2015

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“…6 displays the Fe 2p XPS of NFO along with reference spectra of α-Fe 2 O 3 , Fe 3 O 4 , and FeO for comparison. 42,43 The Fe 2p 7 and 8. The agreement between experimental and computed spectra for Ni is almost perfect, indicating that Ni 2+ occupies solely octahedral sites.…”

Section: Cation Distribution and Element Resolved Magnetic Momentsmentioning

confidence: 99%

Physical characteristics and cation distribution of NiFe2O4 thin films with high resistivity prepared by reactive co-sputtering

Klewe¹,

Meinert²,

Boehnke³

et al. 2014

Journal of Applied Physics

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We fabricated NiFe 2 O 4 thin films on MgAl 2 O 4 (001) substrates by reactive dc magnetron co-sputtering in a pure oxygen atmosphere at different substrate temperatures. The film properties were investigated by various techniques with a focus on their structure, surface topography, magnetic characteristics, and transport properties. Structural analysis revealed a good crystallization with epitaxial growth and low roughness and a similar quality as in films grown by pulsed laser deposition. Electrical conductivity measurements showed high room temperature resistivity (12 Ωm), but low activation energy, indicating an extrinsic transport mechanism. A band gap of about 1.55 eV was found by optical spectroscopy. Detailed x-ray spectroscopy studies confirmed the samples to be ferrimagnetic with fully compensated Fe moments. By comparison with multiplet calculations of the spectra we found that the cation valencies are to a large extent Ni 2+ and Fe 3+ .

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“…On the other hand, the presence of a defective iron monoxide phase at the interface would result in a large roughness, which is at variance with the experimental results. In a previous study on this same system [27] a 4nm thick Fe2O3 layer was first grown and then annealed at 675 K in UHV first and in oxygen next. This led to a magnetite film, which lacked of the interfaces sharpness and perhaps the single phase requirement indispensable for obtaining the desired electronic properties.…”

Section: 2morphology and Structurementioning

confidence: 99%

“…We employed a similar method for growing high quality (001) magnetite ultrathin films on Ag(001). The formation of iron oxides on Ag(001) has already been investigated, evidencing different phases as function of the O2 pressure during annealing [27]. A possible drawback with this substrate is the presence of a moderate intermixing at the interface during Fe/Ag(001) growth at room temperature [28].…”

Section: Introductionmentioning

confidence: 99%