Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 26: CE: Heavy Fermions
TT 26.8: Talk
Wednesday, March 24, 2010, 16:00–16:15, H21
Scanning Tunneling Spectroscopy studies of heavy fermion metals — •Stefan Ernst1, Steffen Wirth1, Cornelius Krellner1, Christoph Geibel1, Frank Steglich1, Zachary Fisk2, John L. Sarrao3, and Joe D. Thompson3 — 1Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany — 2Department of Physics and Astronomy, University of California at Irvine, USA — 3Los Alamos National Laboratory, Los Alamos, USA
We report Scanning Tunneling Microscopy/Spectroscopy (STM/S) experiments on single crystals of the heavy fermion intermetallic compounds CeCoIn5, CeIrIn5, and YbRh2Si2. The tunneling experiments were conducted at temperatures down to 300 mK under ultra–high vacuum conditions. Methods have been established to facilitate in-situ sample cleaving.
CeCoIn5 and CeIrIn5 exhibit unconventional superconductivity (SC) at ambient pressure. A gap compatible with d-wave symmetry of the order parameter was observed in the conductance spectra of CeCoIn5. The presence of a gap–like feature in a temperature range above Tc may indicate the existence of a precursor state to SC. Based on atomically resolved topography data, the possible influence of a modified surface structure on STS is discussed.
For the case of YbRh2Si2, we speculate that the tunneling spectra reveal signatures of a Kondo resonance related to the Yb ions.