Atomic Structure of Cr₂O₃/Ag(111) and Pd/Cr₂O₃/Ag(111) Surfaces: A Photoelectron Diffraction Investigation

A detailed investigation concerning the atomic structure of Cr₂O₃ and Pd/Cr₂O₃ ultrathin films deposited on a Ag(111) single crystal is presented. The films were prepared by MBE (molecular beam epitaxy) and characterized <i>in situ</i> by LEED (low energy electron diffraction), XPS (X-ray photoelectron spectroscopy), and XPD (X-ray photoelectron diffraction). Evidences of rotated domains and an oxygen-terminated Cr₂O₃/Ag­(111) surface were observed, along with significant contractions of the oxide’s outermost interlayer distances. The deposition of Pd atoms on the Cr₂O₃ surface formed a four-monolayer film, <i>fcc</i> packed and oriented in the [111] direction, which presented changes in monolayer spacing and lateral atomic distance compared to the expected values for bulk Pd. The observed surface structure may shed light on new physical properties such as the induced magnetic ordering in Pd atoms