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O: Fachverband Oberflächenphysik

O 36: Poster Session III: Electronic structure of surfaces: Spectroscopy, surface states I

O 36.1: Poster

Tuesday, March 2, 2021, 10:30–12:30, P

Phonon mediated tunneling into a 2D electron gas on the Be(0001) surface — •Hermann Osterhage, Karoline Oetker, Roland Wiesendanger, and Stefan Krause — Department of Physics, University of Hamburg, Germany

Beryllium is a very unique element among the metals. Whereas the bulk behaves almost like a semiconductor, the (0001) surface is much more metallic, originating from electronic surface states. In our experiments, the clean Be(0001) surface was investigated using scanning tunneling spectroscopy at low temperatures [1]. A pronounced surface state is identified, additionally manifested by the observation of bias-dependent standing wave patterns. Fourier analysis reveals a parabolic dispersion, being characteristic for Friedel oscillations. In contrast to previous studies [2], no indications for the formation of a charge density wave were observed.

Our spectroscopy data reveal symmetric steps in the tunneling conductance around the Fermi level, which we assign to the opening of inelastic tunneling channels via coupling to phonon modes. The Be(0001) surface is found to represent an almost ideal model system to shed light on the details of fundamental electron-electron and electron-phonon interactions in low dimensions.

[1] H. Osterhage et al. (submitted).

[2] P. T. Sprunger et al., Science 275, 1764 (1997).