Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 8: Ultrafast Electron Dynamics I: Surfaces and Interfaces (joint session O/MA)

O 8.1: Talk

Monday, March 16, 2020, 10:30–10:45, TRE Phy

Electron dynamics of surface states in momentum space on Cu and Au — •Lukas Hellbrück, Tobias Eul, Martin Aeschlimann, and Benjamin Stadtmüller — Department of Physics and Research Center Optimas, University of Kaiserslautern, Germany

For the development of nanoscale electronic and spintronic devices, it is critical to understand electronic dynamics in solid states systems and at interfaces. Of particular interest is the correlation between the energy and momentum dissipation mechanisms of the hot carriers and the band structure of the material.

In this work, we employ time-resolved two photon momentum microscopy [1] with monochromatic radiation of about 4.6eV to access the electron dynamics in the excited state energy range of typical noble metal surfaces. From these data, we can extract momentum dependent quasi-particle lifetimes of the electrons, providing insight into momentum dependent scattering processes in these materials.

We focus on the (111) and (110) low-index copper and gold surfaces. These surfaces yield a variety of different states in the unoccupied band structure ranging from resonant and off-resonant bulk transitions to Shockley surface states and image potential states. For these different types of states, we observe lifetime differences of several femtoseconds, which points to a complex momentum dependent lifetime of the electrons, even for simple single crystalline materials.

[1] F. Haag et al., Rev. Sci. Instr. 90, 103104 (2019)