Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 80: Surface Dynamics I

O 80.3: Vortrag

Donnerstag, 3. April 2014, 16:30–16:45, GER 38

A photoinduced change of kF in Bi2212 revealed by femtosecond time- and angle-resolved photoemission spectroscopy — •S. Freutel1, J.D. Rameau2, L. Rettig1, I. Avigo1, S. Thirupathaiah1, M. Ligges1, G.D. Gu2, H. Eisaki3, P.D. Johnson2, and U. Bovensiepen11Faculty of Physics, University of Duisburg-Essen, Duisburg, Germany — 2Brookhaven National Laboratory, New York, USA — 3National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan

Optical excitation and subsequent ultrafast electronic relaxation leads to quasiparticle redistribution, which potentially changes the chemical potential, or the Fermi momentum kF, in systems with non-constant density of states. Here, we report on time- and angle resolved photoemission spectroscopy on optimally doped Bi2212 in the pseudogap phase. We observed a change in kF that appears as a photoinduced change of the effective doping level caused by an electron-hole asymmetry. Along the nodal line this effect scales linearly with the optical excitation density of 35 to 300 µJ/cm2 and peaks at a delay of 100 fs. Since the change in kF relaxes within 1 ps, we consider the excitation of secondary electrons and subsequent electron phonon coupling as the underlying processes. Additional results on chemically underdoped Bi2212 show that the shift in kF increases for larger momenta which suggests a quantitative comparison and discussion of static chemical and transient photoinduced doping.
We acknowledge support by the DFG through SFB616 and the Mercur Research Center Ruhr through PR-2011-0003.

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