Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 54: Nanostructured surfaces and thin films

O 54.3: Vortrag

Mittwoch, 11. März 2026, 11:00–11:15, HSZ/0201

Imaging the transition from diffusive to Landauer resistivity dipoles — •Serhii Kovalchuk^{1, 2}, David Kämpfer^{1, 3, 4}, Jonathan K. Hofmann^{1, 3, 4}, Timofey Balashov^{1, 3, 5}, Vasily Cherepanov¹, Bert Voigtländer^{1, 3, 4}, Ireneusz Morawski², F. Stefan Tautz^{1, 3, 4}, and Felix Lüpke^{1, 6} — ¹Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany — ²Institute of Experimental Physics, University of Wrocław, 50-204 Wrocław, Poland — ³Jülich Aachen Research Alliance (JARA), Fundamental of Future Information Technology, 52425 Jülich, Germany — ⁴Lehrstuhl für Experimentalphysik IV A, RWTH Aachen University, 52074 Aachen, Germany — ⁵Lehrstuhl für Experimentalphysik II A, RWTH Aachen University, 52074 Aachen, Germany — ⁶II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany

A point-like defect in a current-carrying conductor produces an electrochemical potential dipole that opposes the applied field. When the carriers mean free path is shorter than the defect size, the dipole reflects diffusive transport; when it is longer, ballistic scattering leads to a size-independent residual resistivity dipole as predicted by Rolf Landauer.

We investigate this behaviour around nanoscale holes in thin Bi films on Si(111) using scanning tunneling potentiometry. The measured dipole amplitudes show a clear crossover from linear to constant scaling with decreasing hole size, marking the transition from diffusive to Landauer-type dipoles. This crossover allows us to extract the Fermi wave vector and estimate the carrier mean free path in the Bi films.

Keywords: residual resistivity dipole; scanning tunneling potentiometry; electronic transport; Landauer dipoles