SurfaceScience21 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Poster Session III: Poster to Mini-Symposium: Ultrafast surface dynamics at the space-time limit I

O 41.3: Poster

Dienstag, 2. März 2021, 10:30–12:30, P

Heavy fermion dynamics in semimetallic and insulating phases — •Chul-hee Min¹, Michael Heber², Simon Müller³, Lukas Wenthaus², Steffen Palutke², Dmytro Kutnyakhov², Federico Pressacco², Lenart Dudy⁴, Matthieu Silly⁴, Hendrik Bentmann³, Kiana Baumgärtner³, Woojae Choi⁵, Yong Seung Kwon⁵, Markus Scholz⁶, Friedrich Reinert³, and Kai Rossnagel^1,2 — ¹IEAP, CAU Kiel, Germany — ²DESY, Hamburg, Germany — ³EP7 and ct.qmat, University of Würzburg, Germany — ⁴Synchrotron-SOLEIL, Saint-Aubin, France — ⁵Dep. of EMS, DGIST, South Korea — ⁶EuXFEL, Schenefeld, Germany

Due to time–energy correlation, heavy fermion systems with hard-to-detect meV energy scales are expected to show relatively slow dynamics on ps time scales, which are relatively easy to measure. Using the free-electron laser FLASH, we have performed time-resolved pump-probe photoemission spectroscopy (PES) of mixed valent TmSe_1−xTe_x at a probe photon energy where the photoionization cross-section of the localized 4f states is two orders of magnitude higher than the ones of the other states. The system consists of two magnetic 4f¹² and 4f¹³ configurations in the ground state and can be tuned from a semimetallic to an insulating phase via x without destroying the periodicity of the Tm ions. Here, we present and discuss the transient dynamics of the 4f states near E_F showing a remarkably strong dependence on x. Particularly, we identify a renormalized 4f peak whose time-domain signature is distinct from all other 4f multiplet peaks.