Structural and vibrational properties of two-dimensionalMnxOylayers on Pd(100): Experiments and density functional theory calculations

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 Pd͑100͒ 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 MnO͑111͒-like O-Mn-O trilayers, whereas the other two have a lower oxygen content and are based on a MnO͑100͒-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.

Self-organized chromium oxide monolayers on Fe(001)

“…We recall that a c(4 × 2) superstructure like the one observed here has been reported for a number of rocksalt-type oxides on Pd(001). 19,61,62 In those cases, the occurrence of metal vacancies has been proposed as a mechanism able to compensate the compressive stress due to a large lattice mismatch between the substrate and the overlayer. In the present case, however, the interfacial strain is unlikely to be relevant in inducing cation vacancies.…”

Two-dimensional manganese oxide nanolayers on Pd(100): the surface phase diagram

“…Implicitly, this suggests an oxide film consisting of alternately stacked layers with quasi-hexagonal symmetry containing only one single atom species, as it is realized in the MnO(111) structure. This will be discussed in detail in reference [12].…”

“…The atomistic models of the different phases as derived by combining the experimental high-resolution STM and vibrational electron energy loss spectroscopy (HREELS) data with ab initio density functional theory calculations will be presented in a forthcoming publication [12]. We find at least nine different 2D MnO x phases on Pd(100), which are novel in terms of the known Mn oxide bulk crystal structures and which are stabilized by the metal-oxide interface and the confinement in the direction perpendicular to the 3 analysis stages in the UHV chamber.…”

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

“…Outstanding examples are the coupling between strain and spin orientation [1], the tuning of the catalytical activity upon selective modulation of the work function [2] and the structural flexibility related to substrate-overlayer matching [3,4]. Notably, metal templates such as Ag(1 0 0), Pt(1 1 1) and Pd(1 0 0) can turn into metallic the otherwise insulating character of TMOs, thus rendering this class of system accessible to fundamental studies based on scanning tunneling microscopy (STM) and electron spectroscopy experiments.…”