Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 99: Scanning Probe Methods III

O 99.4: Vortrag

Freitag, 4. April 2014, 11:15–11:30, GER 38

Determination of the electron-phonon coupling in ultra-thin Pb films with STM — Michael Schackert¹, Tobias Märkl¹, •Jasmin Jandke¹, Martin Hölzer², Sergey Ostanin², Eberhard K.U. Gross², Arthur Ernst^2,3, and Wulf Wulfhekel¹ — ¹Karlsruhe Institut of Technology, Physikalisches Instiut, Wolfgang-Gaede Straße 1, 76131 Karlsruhe, Germany — ²Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany — ³Wilhelm-Ostwald Institut für Physikalische und Theoretische Chemie, Linnéstraße 2, Universität Leipzig, 04103 Leipzig, Germany

In conventional superconductors, Cooper pairs form due to electron-electron interaction via virtual phonon exchange. A central quantity in this process is the effective phonon spectrum, also known as Éliashberg function which determines the superconducting properties of the material. Using scanning tunneling microscopy (STM) below 800 mK in UHV we found a new method to locally determine the Éliashberg function directly by performing the inelastic tunneling spectroscopy in the normal state. As a first model system we investigated thin Pb islands on Cu(111), wich are in the normal-state due to the proximity effect and therefore the STM-ITS signal is not superposed by the signature of the SC gap. We find a pronounced dependence of the electron-phonon coupling on the island thickness which is in good agreement with ab initio calculations.