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TT: Fachverband Tiefe Temperaturen

TT 34: Correlated Electrons: f-Electron Systems and Heavy Fermions 1

TT 34.2: Vortrag

Mittwoch, 18. März 2020, 09:45–10:00, HSZ 204

Temperature and Momentum Dependences of the Kondo Peak in the Heavy-Fermion System CeRh₂Si₂ — •Georg Poelchen¹, Susanne Schulz¹, Monika Güttler¹, Max Mende¹, Alexander Generalov², Christoph Geibel³, Cornelius Krellner⁴, Steffen Danzenbächer¹, James W Allen⁵, Clemens Laubschat¹, Yuri Kucherenko⁶, and Denis V Vyalikh^{7, 8} — ¹IFMP, TU Dresden, Germany — ²Max IV Laboratory, Lund, Sweden — ³MPI for Chemical Physics of Solids, Dresden, Germany — ⁴Kristall- und Materiallabor, Goethe-Universität Frankfurt, Germany — ⁵Randall Laboratory, University of Michigan, USA — ⁶Institute for Metal Physics, National Academy of Science, Ukraine — ⁷DIPC, San Sebastian, Spain — ⁸IKERBASQUE, Bilbao, Spain

Ultra-violet angle-resolved photoemission spectroscopy (UV-ARPES) was used to explore the temperature dependences of different surface terminations of the antiferromagnetic Kondo lattice CeRh₂Si₂. Spectra were taken from Ce- and Si-terminated surfaces in a wide temperature range, and reveal characteristic 4f patterns for weakly (surface) and strongly (bulk) hybridized Ce, respectively. Surprisingly, the temperature dependence of the Fermi level peak points to a considerably larger effective Kondo temperature at the surface, likely due to a higher local-moment effective degeneracy.

Further, we derived the k-resolved dispersion of the Kondo peak which is also found to be distinct due to different sets of itinerant bands to which the 4f states couple, highlighting that the Kondo physics vary remarkably between surface and bulk of the Kondo lattice material.