Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 60: Correlated Electrons: f-Electron Systems
TT 60.10: Vortrag
Donnerstag, 23. März 2017, 12:00–12:15, HSZ 201
Microwave response of CeCu2Si2 — •Markus Thiemann1, Martin Dressel1, Silvia Seiro2, Christoph Geibel2, Nicholas Lee-Hone3, David Broun3,4, and Marc Scheffler1 — 11. Physikalisches Institut, Universität Stuttgart, Germany — 2Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany — 3Department of Physics, Simon Fraser University, Burnaby, Canada — 4Canadian Institute for Advanced Research, Toronto, Canada
CeCu2Si2 is a heavy fermion compound, exhibiting a onset of superconductivity (Tc ≈ 0.6K) at a quantum critical point. Although superconductivity in this compound was discoverd over 30 years ago, its origin and the symmetry of the order parameter still remain unclear. While it was long believed that the order parameter had a d-symmetry, supported by neutron scattering experiments and NQR, recent specific heat measurements indicate fully gapped multigap superconductivity. Since the relevant energy scales of this compound are in the µeV regime, microwave measurements are an adequate technique to reveal intrinsic electronic properties of this system.
We performed microwave resonator measurements in a frequency and temperature range from 2.5GHz to 20GHz and 0.1K to 10K. This enabled us to determine the complex optical conductivity in the metallic as well as the superconducting state. In the metallic state, above 0.6K we see signs of the heavy fermion state arising, pushing the scattering rate towards our spectral range. In the superconducting state the absense of a coherence peak and the temperature dependence of the superfluid density point towards unconventional superconductivity.