Cobalt oxide nanolayers on Pd(100): The thickness-dependent structural evolution

Gragnaniello, Luca; Agnoli, Stefano; Parteder, G.; Barolo, Andrea; Bondino, Federica; Allegretti, Francesco; Surnev, S.; Granozzi, Gaetano; Netzer, F.P.

doi:10.1016/j.susc.2010.08.012

Cited by 41 publications

(62 citation statements)

References 49 publications

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“…2 are straightforwardly assigned to O 2p states but the region below 5 eV is more difficult to interpret due to the mixed TM 3d-O 2p states. VB spectra qualitatively agree with the previous studies 21,40,50,51 , in the present work the spectral features are much better resolved. Pt 5d states still contribute to the spectra taken in normal electron emission geometry whereas they nearly vanish in grazing geometry.…”

Section: Discussionsupporting

confidence: 92%

“…In addition, BE of Co 2p 3/2 main line peak position appears to be slightly lower than BE of Co 2+ of the bulk systems 9 . Despite the differences in the intensity ratios of the main lines to the satellite peaks, c(4×2) and (9×2) phases of the cobalt oxides grown on Pd(100) demonstrate similar BEs 40 . XPS spectrum of FeO films is identical to the previously published data 21 .…”

Section: Discussionmentioning

confidence: 93%

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Identification of the electronic structure differences between polar isostructural FeO and CoO films by core-level soft x-ray spectroscopy

et al. 2013

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The electronic properties of the FeO and CoO single layer thin films on Pt(111) were examined by core level soft X-ray spectroscopy. These oxygen terminated films are bilayer-thick and isostructural, Pt, Fe-Co, and O atoms stacked with small lateral shifts due to incommensurate relation with Pt(111). Probing occupied and unoccupied states projected on the oxygen atoms revealed states at the Fermi level suggesting orbital mixing with the metal substrate and also indicated an anisotropy in transition metal-oxygen bonding geometry. The differences in the core level spectral features were attributed to the substrate induced modification of the charge transfer energy and with an additional valence electron on Co.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 93%

Identification of the electronic structure differences between polar isostructural FeO and CoO films by core-level soft x-ray spectroscopy

et al. 2013

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“…24) and Pd(100) (Ref. 25), was already studied mainly by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). The growth of cobalt oxide on Pt(111) at room temperature (RT) was investigated employing reflection high-energy electron diffraction (RHEED) and spectroscopic techniques.…”

Section: Introductionmentioning

confidence: 99%

Growth of ultrathin cobalt oxide films on Pt(111)

et al. 2011

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Cobalt surface oxides where grown on Pt(111) by depositing Co and dosing with molecular oxygen at temperatures ranging between 300 K and 740 K. Oxidation of 1 monolayer (ML) Co results in a two-dimensional (2D) moiré structure, observed both using low energy electron diffraction and scanning tunneling microscopy, and interpreted as a polar (oxygen terminated) CoO(111) atomic bilayer. With respect to bulk CoO, it is expanded by 2.7±0.5% in the surface plane. An almost flawless moiré pattern is obtained after a final step of annealing at 740 K in oxygen. Insufficient oxidation leads to defects in the moiré pattern, consisting of triangular dislocation loops of different sizes; the smaller ones occupying one half of the moiré cell. Low-temperature annealing (450 K) can be used to create a zigzag phase, which is mainly observed in 1-ML thick areas after several cycles of Co deposition (1 ML each) and oxidation at 10 -7 mbar. The CoO films obtained by deposition/oxidation cycles exhibit Stranski-Krastanov growth; the structure of the 2D layer in between the islands depending on the thermal treatment. After annealing at 740 K it exhibits the moiré pattern, while the zigzag phase was observed after low-temperature annealing. The second monolayer consists of a moiré pattern different from that of the 1st layer, presumably a wurtzite-like structure. Above the 3rd layer, we observe only small 3D islands, which exhibit a band gap. We have also studied oxidation of surface alloys obtained by depositing Co and annealing. On these surfaces, we found a quasi-(3×3) reconstruction. Structure models are presented for all phases observed, and we argue that some of the moiré-like structures might be useful as templates for metal cluster growth.

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“…The reader should note that structurally equivalent c(4 × 2) phases were found also for other oxide/substrate combinations. [2][3][4][5][6][7][8][9] The question arising upon our previous finding is, how local is this interface chemistry driven effect? In order to answer this we prepared a suitably patterned substrate so that the growth of CoO domains in contact with either bare iridium or an interfacing Co layer is possible.…”

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confidence: 93%