Observation of interfering Bloch waves
Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195
2 Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA Oak Ridge National Laboratories - Oak Ridge, TN 37831-6057, USA
Accepted: 26 May 1997
We have observed anisotropic standing waves on the Be(100 surface using a low-temperature scanning tunnelling microscope (STM). Such charge density oscillations result from interference of electronic states near scattering centers. Since the charge density on Be(100 is mainly provided by a surface state located near the edge of the first Brillouin zone, the wave functions are significantly different from plane waves. It is shown how this difference is reflected in the STM images. By numerical post-processing we find that the observed wave patterns exhibit a multiperiodic structure with individual periods differing by inverse lattice vectors. This result constitutes a direct experimental illustration of the Bloch theorem for electrons in a periodic potential.
PACS: 73.20.At – Surface states, band structure, electron density of states / 72.10.Fk – Scattering by point defects, dislocations, surfaces, and other imperfections (including Kondo effect)
© EDP Sciences, 1997