Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 5: Electronic structure I

O 5.1: Vortrag

Montag, 27. März 2006, 11:15–11:30, WIL A317

Probing of bulk band edges by STM: An ab initio analysis — •Alexey Dick and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany

Scanning tunneling microscopy (STM) is an extensively used surface-sensitive tool that allows to address an ever extending range of surface phenomena. Recently it became possible to study electron dynamics by analyzing electron standing wave patterns created in the vicinity of surface imperfections. In the past these studies had been mainly restricted to surface states since bulk states have been assumed to decay too fast in the vacuum region accessed by STM.

To analyze whether STM can be extended to access bulk properties such as the dispersion of the projected bulk band edge (BBE), we have performed a theoretical STM study on various noble metal (110) surfaces. A repeated slab geometry and density functional theory based on a plane-wave pseudopotential approach have been employed to accurately describe surface properties.

A careful analysis of our results explains well recent experimental studies on silver (110) surfaces [1]. It shows that probing of the BBE is possible due to coupling of the bulk and surface states and an enhancement of the bulk state density at the edge of the projected bulk bands. Such an enhancement occurs due to the bulk band-folding in the direction perpendicular to a surface. Since the underlaying effect is general, our results can be used to understand the resolution of the BBE on other metallic surfaces.

[1] J.I. Pascual et al., submitted to Phys. Rev. Lett.