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ABSTRACT: The growth of ultrathin two-dimensional manganese oxide nanostripes on vicinal Pd(1 1 N) surfaces leads to particular stable configurations for certain combinations of oxide stripe and substrate terrace widths. Scanning tunneling microscopy and high-resolution low-energy electron diffraction measurements reveal highly ordered nanostructured surfaces with excellent local and long-range order. Density functional theory calculations provide the physical origin of the stabilization mechanism of 'magic width' stripes in terms of a finite-size effect, caused by the significant relaxations observed at the stripe boundaries.
Journal of Physics Condensed Matter 02/2012; 24(4):042001. · 2.55 Impact Factor
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ABSTRACT: Two-dimensional manganese oxide layers have been grown on Pd(100) and have been characterized by means of scanning tunnelling microscopy, low energy electron diffraction and x-ray photoelectron spectroscopy (XPS). The complex surface phase diagram of MnO(x) on Pd(100) is reported, where nine different novel Mn oxide phases have been detected as a function of the chemical potential of oxygen μ(O). Three regions of the chemical potential of oxygen can be identified, in which structurally related oxide phases are formed, often in coexistence at the surface. The different regions of μ(O) are reflected in the oxidation states of the respective Mn oxide nanolayers as revealed by the Mn 2p and O 1s XPS binding energies. The MnO(x) nanolayers form two-dimensional wetting layers and it is speculated that they mediate the epitaxial growth of MnO on Pd(100) by providing structurally graded interfaces.
Journal of Physics Condensed Matter 04/2009; 21(13):134008. · 2.55 Impact Factor
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ABSTRACT: The surface stabilized MnO(100)-like monolayer, characterized by a regular c(4 x 2) distribution of Mn vacancies, is studied by hybrid functionals and discussed in the light of available scanning tunneling microscopy and high-resolution electron energy loss spectroscopy data. We show that the use of hybrid functionals is crucial to account for the intermingled nature of magnetic interactions, electron localization, structural distortions, and surface phonons. The proposed Pd(100) supported Mn(3)O(4) structure is excellently compatible with the experiments previously reported in literature.
The Journal of chemical physics 04/2009; 130(12):124707. · 3.09 Impact Factor
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ABSTRACT: The surface stabilized MnO(100)-like monolayer, characterised by a regular c(4x2) distribution of Mn vacancies, is studied by hybrid functionals and discussed in the light of available scanning tunneling microscopy and high-resolution electron energy loss spectroscopy data. We show that the use of hybrid functionals is crucial to account for the intermingled nature of magnetic ineractions, electron localization, structural distortions and surface phonons. The proposed Pd(100) supported Mn3O4 structure is excellently compatible with the experiments previously reported in literature. Comment: 16 pages, 5 figures
02/2009;
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ABSTRACT: Using different experimental techniques combined with density functional based theoretical methods we have explored the formation of interface-stabilized manganese oxide structures grown on Pd(100) at (sub)monolayer coverage. Amongst the multitude of phases experimentally observed we focus our attention on four structures which can be classified into two distinct regimes, characterized by different building blocks. Two oxygen-rich phases are described in terms of MnO(111)-like O-Mn-O trilayers, whereas the other two have a lower oxygen content and are based on a MnO(100)-like monolayer structure. The excellent agreement between calculated and experimental scanning tunneling microscopy images and vibrational electron energy loss spectra allows for a detailed atomic description of the explored models. Comment: 14 pages, 11 figures
11/2008;
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ABSTRACT: We use scanning tunneling microscopy (STM) and high-resolution core-level spectroscopy (XPS) measurements to study the initial oxidation of vicinal Pd(100) surfaces exhibiting close-packed (111) steps. The XPS data analysis is supported by detailed surface-core level shift calculations based on densityfunctional theory. Both STM images and the XPS spectra are found to be perfectly consistent with a characteristic zigzag O decoration of the Pd steps predicted by a preceding cluster-expansion based theoretical study [Y. Zhang and K. Reuter, Chem. Phys. Lett. 465, 303 (2008)]. Continued oxygen uptake leads to the additional stabilization of a p(2×2)-O overlayer on the Pd(100) terraces, and ultimately to step bunching with the resulting large Pd(100) terraces covered by the PdO(101) surface oxide.
Surface Science, v.604, 1813-1819 (2010).
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ABSTRACT: Using different experimental techniques combined with density functional based theoretical methods we have explored the formation of interface-stabilized manganese oxide structures grown on Pd100 at sub-monolayer coverage. Among the multitude of phases experimentally observed we focus our attention on four structures which can be classified into two distinct regimes, characterized by different building blocks. Two oxygen-rich phases are described in terms of MnO111-like O-Mn-O trilayers, whereas the other two have a lower oxygen content and are based on a MnO100-like monolayer structure. The excellent agreement be-tween calculated and experimental scanning tunneling microscopy images and vibrational electron-energy-loss spectra allows for a detailed atomic description of the explored models.
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