Electron Resonances in Sharp Tips and Their Role in Tunneling Spectroscopy

Publisher Website
Google Scholar
Abstract
The influence of the shape and electronic structure of the tip in scanning tunneling spectroscopy is studied by a combined theoretical and experimental approach. Tunneling conductance spectra of a Cu(111) surface are used to detect and characterize the electronic states of W tips. The characteristic tunneling conductance of the Cu(111) surface state is the only feature present in spectra recorded with a blunt tip, while spectra obtained with sharp tips display also tip resonances. By means of a self-consistent tight-binding model of realistic tip structures we show that a sharp W tip exhibits, in contrast with blunt tips, narrow resonant states around the Fermi level.