Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 48: Surface dynamics I

O 48.5: Talk

Wednesday, March 24, 2010, 11:30–11:45, H40

Momentum dependent electron and hole relaxation dynamics in EuFe₂As₂ — •L. Rettig¹, R. Cortes¹, S. Thirupathaiah², U. Bovensiepen^1,3, M. Wolf¹, H. A. Duerr², P. Gegenwart⁴, T. Wolf⁵, and J. Fink^2,6 — ¹Freie Universität Berlin, D-14195 Berlin — ²Helmholtz-Zentrum Berlin, D-12489 Berlin — ³Universität Duisburg-Essen, D-47048 Duisburg — ⁴Georg-August-Universität Göttingen, D-37077 Göttingen — ⁵Karlsruhe Institute of Technology, D-76021 Karlsruhe — ⁶Leibniz-Institute for Solid State and Materials Research Dresden, D-01171 Dresden

The influence of the electronic bandstructure on the fundamental relaxation processes of excited carriers leading to intra- and interband scattering is of fundamental interest in solid state physics. Here, we report on fs time- and angle-resolved photoemission spectroscopy (trARPES) on the parent compound EuFe₂As₂ of the new class of FeAs based high-T_c superconductors. Using intense fs laser pulses (hν=1.5 eV), part of the electronic population is excited to states above the Fermi level. The transient evolution of both occupied and unoccupied states is probed by energy- and angle-resolved photoelectron spectroscopy using a time-delayed ultraviolet pulse (hν=6.0 eV). Upon excitation, occupied states around the hole-pocket at the Γ-point of the Brillouin zone become partially depopulated by excited holes, whereas electrons are filling the empty states within the hole-pocket. The timescales of electron and hole dynamics within this band differ drastically and cannot be explained solely by intraband e-h pair generation, but an additional interband excitation channel has to be considered.