Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 41: Correlated Electrons: Quantum-Critical Phenomena

TT 41.7: Vortrag

Mittwoch, 22. März 2017, 11:00–11:15, HSZ 204

Coherent Emergence of a Quantum Critical Heavy Fermion Groundstate — •Christoph Wetli1, Johann Kroha2, Oliver Stockert3, Hilbert von Löhneysen4, Kristin Kliemt5, Cornelius Krellner5, and Manfred Fiebig11Department of Materials, ETH Zürich — 2Institute of Physics, Bonn University — 3MPI for Chemical Physics of Solids, Dresden — 4Institute of Solid State Physics, KIT — 5Institute of Physics, Goethe University Frankfurt

Kondo quasiparticles in heavy-fermion metals have an outstandingly long lifetime. However, near a quantum phase transition, the quasiparticles may disintegrate and give way to an exotic state of matter where the very concept of a particle breaks down. We investigate the emergence of this quantum critical behavior in a time-resolved Terahertz reflection experiment. Due to the non-ionizing nature of Terahertz radiation, we directly monitor the formation dynamics of a strongly correlated groundstate in a time-resolved experiment, while simultaneously monitoring the spectral weight and the Kondo temperature. In the quantum critical CeCu5.9Au0.1 compound, the heavy-fermion state reconvenes after 5.8 ps under the emission of a temporally delayed, yet phase-coherent reflex. When the temperature is lowered, the changing dynamics indicates the emergence of the unconventional quantum critical state. A decrease in amplitude and an increase in delay of the reflex reveals that the quasiparticle weight collapses while the Kondo temperature reduces but remains finite.

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