Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 75: Ultrafast Electron and Spin Dynamics
O 75.2: Vortrag
Mittwoch, 22. März 2017, 15:15–15:30, TRE Phy
Ultrafast photoinduced valence transition in the heavy-fermion compound YbInCu4 — •Lars-Philip Oloff1, Lukas Wenthaus2, Kerstin Hanff1, Giuseppe Mercurio3, Michael Bauer1, Wilfried Wurth2,3, and Kai Rossnagel1 — 1Institut für Experimentelle und Angewandte Physik, Universität Kiel, 24098 Kiel, Germany — 2DESY Photon Science, 22607 Hamburg, Germany — 3Department of Physics and Center for Free-Electron Laser Science CFEL, University of Hamburg, 22761 Hamburg, Germany
Upon cooling to a temperature below 42 K, the heavy-fermion compound YbInCu4 undergoes an isostructural transition from a semimetallic, paramagnetic phase with an Yb valence of +3 to a metallic, non-magnetic phase with an Yb valence of +2.85. Here, we combine HHG and FEL-based time-resolved photoemission spectroscopy techniques to gain novel insights into the valence transition in the (sub-)surface region. Through the combination of time-resolved ARPES and time-resolved XPS, we are able to directly track different characteristic spectroscopic signatures of the photoinduced valence change in the (transient) valence and core electronic structure on the femtosecond to picosecond timescale. Our results constitute the first direct experimental observation of an ultrafast photoinduced valence change in a heavy-fermion compound.