Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 13: Ultrafast Electron Dynamics at Surfaces and Interfaces II
O 13.5: Vortrag
Montag, 18. März 2024, 16:15–16:30, MA 041
Thermal boundary conductance of ultrathin epitaxial Pb films on Si(111) — Christian Brand1, Tobias Witte1, Mohammad Tajik1, Jonas D. Fortmann1, •Michael Horn-von Hoegen1, Laurenz Rettig1,2, and Uwe Bovensiepen1 — 1University of Duisburg-Essen, Duisburg, Germany — 2Fritz Haber Institute, Berlin, Germany
The non-equilibrium dynamics of electrons in a metal subsequent to excitation with a fs-laser pulse couple to other degrees of freedom during the relaxation phase of the system. Here we have studied the electron and lattice dynamics in ultrathin Pb films grown on Si(111) by means of time-resolved photoemission spectroscopy and reflection high-energy electron diffraction. After thermalization of the electron and lattice system, the transient cooling of the film is determined by heat transport across the interface into the substrate, i.e., by the thermal boundary conductance (TBC) on time scales of a few 100 ps. We experimentally find for crystalline Pb films with low defect density at a base temperature of 19.3 K a TBC of less than 2 MW/m2K. We discuss the results in terms of diffuse and acoustic mismatch models.
Keywords: ultrafast dynamics; thermal boundary conductance; ultrathin metallic films; electron-phonon coupling; heat transport