Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 57: Poster Wednesday: Electronic Structure

O 57.3: Poster

Wednesday, September 7, 2022, 18:00–20:00, P4

Line shape analysis of the resonant eigenstates in a quantum corral by means of tunneling spectroscopy and non contact AFM — •Marco Weiss, Michael Roessner, Fabian Stilp, and Franz J. Giessibl — Institute of Experimental and Applied Physics, University of Regensburg, Germany

Back in 1993 Crommie et al. [1] arranged 48 Fe adatoms on a Cu(111) surface in a circle with a diameter of 14.26 nm. This quantum corral confines surface electrons in a circular potential well. Past investigations with scanning tunneling microscopy revealed energetically discrete eigenstates that spatially appear as Bessel functions. But these studies on the Fe quantum corral showed unwanted movement of the corral walls during spectroscopic measurements. [1]

Instead of Fe, we used CO molecules to provide the corral with more stable walls. This permitted us to access a larger voltage window and allowed for a detailed line shape analysis of the corrals eigenenergy levels. Surprisingly, we discovered a large Gaussian broadening of the eigenstates.

We also acquired nc-AFM data of the corral. As we have previously done, we determined the occupation of electronic states that cross the Fermi level [2]. Similar to our previous work, we observed that the presence of the probe tip shifts the energy of the electronic states under study. In this work, we show that we can also use the AFM data to estimate the lifetime (i.e. the spectral width) of these states.

[1] M. F. Crommie et al., Science 262, 218-220 (1993)

[2] F. Stilp et al., Science 372, 1196-1200 (2021)