Scanning tunneling spectroscopy of subsurface Ag and Ge impurities in copper. (25th November 2021)

• Record Type: Journal Article
• Authors: Kotzott, Thomas; Bouhassoune, Mohammed; Prüser, Henning; Weismann, Alexander; Lounis, Samir; Wenderoth, Martin
• Is Part Of: New journal of physics. Volume 23:Number 11(2021)
• Publication Date: 2021-11-25
• Subjects: scanning tunneling spectroscopy -- Korringa–Kohn–Rostoker Green function method -- dilute alloy -- electron focusing -- Friedel oscillations -- scattering phase shift -- electronic structure renormalization; Physics -- Periodicals; Physics; Periodicals; 530.05
• DOI: 10.1088/1367-2630/ac3681
• Languages: English
• ISSNs: 1367-2630

Abstract

Abstract: We investigate single Ge and Ag impurities buried below a Cu(100) surface using low temperature scanning tunneling microscopy. The interference patterns in the local density of states are surface scattering signatures of the bulk impurities, which result from 3D Friedel oscillations and the electron focusing effect. Comparing the isoelectronic d scatterer Ag and the sp scatterer Ge allows to distinguish contributions from impurity scattering and the host. Energy-independent effective scattering phase shifts are extracted using a plane wave tight-binding model and reveal similar values for both species. A comparison with ab initio calculations suggests incoherent sp scattering processes at the Ge impurity. As both scatterers are spectrally homogeneous, scanning tunneling spectroscopy of the interference patterns yields real-space signatures of the bulk electronic structure. We find a kink around zero bias for both species that we assign to a renormalization of the band structure due to many-body effects, which can be described with a Debye self-energy and a surprisingly high electron–phonon coupling parameter λ . We propose that this might originate from bulk propagation in the vicinity of the surface.