Signature of Fermi surface anisotropy in point contact conductance in the presence of defects

Abstract

In a previous paper (Avotina et al.,Phys. Rev. B Vol.71, 115430 (2005)) we have shown that in principle it is possible to image the defect positions below a metal surface by means of a scanning tunnelling microscope. The principle relies on the interference of electron waves scattered on the defects, which give rise to small but measurable conductance fluctuations. Whereas in that work the band structure was assumed to be free-electron like, here we investigate the effects of Fermi surface anisotropy. We demonstrate that the amplitude and period of the conductance oscillations are determined by the local geometry of the Fermi surface. The signal results from those points for which the electron velocity is directed along the vector connecting the point contact to the defect. For a general Fermi surface geometry the position of the maximum amplitude of the conductance oscillations is not found for the tip directly above the defect. We have determined optimal conditions for determination of defect positions in metals with closed and open Fermi surfaces.

arXiv comment23 pages, 8 figures

References in corpus (6)

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• Method to determine defect positions below a metal surface by STM
• Effect of quantum interference in the nonlinear conductance of microconstrictions
• Quantum interference structures in the conductance plateaus of gold nanojunctions
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• Exact and quasiclassical Green's functions of two-dimensional electron gas with Rashba-Dresselhaus spin-orbit interaction in parallel magnetic field