Strained c(4×2) CoO(100)-like monolayer on Pd(100): Experiment and theory

Allegretti, Francesco; Parteder, G.; Gragnaniello, Luca; Surnev, S.; Netzer, F.P.; Barolo, Andrea; Agnoli, Stefano; Granozzi, G.; Franchini, Cesare; Podloucky, R.

doi:10.1016/j.susc.2009.12.018

Cited by 27 publications

(46 citation statements)

References 28 publications

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“…11 The interest in one-layer-thick oxides is manifold, in particular (i) two-dimensional oxides can be seen as model systems for the oxide/metal interface, allowing investigation by means of high-resolution scanning probe techniques; (ii) the vertical confinement and the elastic and electronic coupling with the metallic substrate allows stabilizing stoichiometries and atomic structures that can differ with respect to the corresponding bulk terminations, with important implications in chemical reactivity, 12,13 adsorption properties, 14 and magnetic ordering 15 of the resulting structures; and (iii) the wetting layer can represent the precursor phase for the growth of thicker films. 16,17 Single layers of transition metal oxides have been stabilized on noble and quasinoble metals such as, for instance, Pd, 18,19 Ag, 20,21 Pt, 22,23 Au, 24 and Ir. 25 In these cases, growth techniques such as reactive deposition (i.e., metal deposition in oxygen atmosphere) and/or postoxidation are typically applied, leading to ordered phases and well-defined oxidemetal interfaces.…”

Section: Introductionmentioning

confidence: 99%

Self-organized chromium oxide monolayers on Fe(001)

et al. 2013

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The oxygen-saturated Fe(001)-p(1 × 1)O surface has been used as a template to stabilize two-dimensional Cr oxides on Fe(001). Cr deposition at 400 • C leads to two different well-ordered phases, depending on the amount of Cr deposited. In the submonolayer regime a novel c(4 × 2) overlayer self-assembles on the Fe(001)-p(1 × 1)O surface, saturating for a coverage of about 0.75 monolayers. This phase becomes unstable for higher coverages, when a ( √ 5 × √ 5)R27 • superstructure emerges. The structural and electronic details of the two one-layer-thick oxides are studied by combining high-resolution scanning tunneling microscopy, low-energy electron diffraction, Auger electron spectroscopy, and density functional theory.

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Section: Introductionmentioning

confidence: 99%

Self-organized chromium oxide monolayers on Fe(001)

et al. 2013

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“…14,18 On Pd(100), two well-defined wetting layer phases have been detected around one monolayer coverage with c(4 × 2) and (9 × 2) surface structures. The c(4 × 2) periodicity with a formal Co 3 O 4 stoichiometry has been shown recently to arise from a periodic array of Co vacancies, which are created in a pseudomorphic CoO(100) monolayer to partially compensate for the strain associated with the lattice mismatch between cobalt monoxide and the Pd substrate, 19 which is ∼9% for bulk CoO but is expected to be reduced at the ML level. 8 Here we concentrate on the 2D monolayer regime and, in particular, investigate the structure and the physical properties of the (9 × 2) cobalt oxide phase by experimental and theoretical means; moreover, its relation to the 2D c(4 × 2) Co oxide phase will be addressed.…”

Section: Introductionmentioning

confidence: 99%

The two-dimensional cobalt oxide (9 × 2) phase on Pd(100)

Gragnaniello

Barcaro

Sementa

et al. 2011

The Journal of Chemical Physics

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The two-dimensional (2D) Co oxide monolayer phase with (9 × 2) structure on Pd(100) has been investigated experimentally by scanning tunneling microscopy (STM) and theoretically by density functional theory (DFT). The high-resolution STM images reveal a complex pattern which on the basis of DFT calculations is interpreted in terms of a coincidence lattice, consisting of a CoO(111)-type bilayer with significant symmetry relaxation and height modulations to reduce the polarity in the overlayer. The most stable structure displays an unusual zig-zag type of antiferromagnetic ordering. The (9 × 2) Co oxide monolayer is energetically almost degenerate with the c(4 × 2) monolayer phase, which is derived from a single CoO(100)-type layer with a Co(3)O(4) vacancy structure. Under specific preparation conditions, the (9 × 2) and c(4 × 2) structures can be observed in coexistence on the Pd(100) surface and the two phases are separated by a smooth interfacial boundary line, which has been analyzed at the atomic level by STM and DFT. The here described 2D Co oxide nanolayer systems are characterized by a delicate interplay of chemical, electronic, and interfacial strain interactions and the associated complexities in the theoretical description are emphasized and discussed.

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“…Indeed, for small strain values (100) oriented oxides were observed for NiO [2] and CoO [3] on Ag(100) ( ¼ 2:0% and 4.1%, respectively), while for large strain as for CoO=Irð100Þ [4][5][6][7][8] and MnO/Rh(100) [9] ( ¼ 9:9% and 14.5%, respectively) films in (111) orientation develop. Yet, in a number of cases (100) films were observed with even considerable nominal strain involved, for example, on Pd(100) for NiO [10][11][12] ( ¼ 6:7%), CoO [13,14] ( ¼ 8:7%), or MnO [15][16][17] ( ¼ 12:5%). In these cases, however, the (100)-type growth starts with a layer exhibiting a cð4 Â 2Þ periodic near rhombic arrangement of transitionmetal vacancies, equivalent to overall TM 4 O 3 stoichiometry, which is supposed to allow for strain relief.…”

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Tuning the Growth Orientation of Epitaxial Films by Interface Chemistry

Gubo

Ebensperger²,

Meyer³

et al. 2012

Phys. Rev. Lett.

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The support of epitaxial films frequently determines their crystallographic orientation, which is of crucial importance for their properties. We report a novel way to alter the film orientation without changing the substrate. We show for the growth of CoO on the Ir(100) surface that, while the oxide grows in (111) orientation on the bare substrate, the orientation switches to (100) by introducing a single (or a few) monolayer(s) of Co between the oxide and substrate. This tunability of the orientation of epitaxial films by the appropriate choice of interface chemistry most likely is a general feature.

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Strained c(4×2) CoO(100)-like monolayer on Pd(100): Experiment and theory

Cited by 27 publications

References 28 publications

Self-organized chromium oxide monolayers on Fe(001)

Self-organized chromium oxide monolayers on Fe(001)

The two-dimensional cobalt oxide (9 × 2) phase on Pd(100)

Tuning the Growth Orientation of Epitaxial Films by Interface Chemistry

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