Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 32: Correlated Electrons: Poster Session
TT 32.15: Poster
Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B
Scanning Tunneling Spectroscopy studies on heavy fermion superconductors — •Stefan Ernst1, Steffen Wirth1, Hirale Jeevan1, Christoph Geibel1, Zachary Fisk2, and Frank Steglich1 — 1Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — 2Department of Physics and Astronomy, UC Irvine
Scanning Tunneling Spectroscopy (STS) is a powerful tool for mapping the local electronic density of states of conducting sample surfaces. Of particular interest are experiments with superconducting (SC) materials, as information about the SC energy gap can directly be obtained. The application of STS to heavy fermion (HF) superconductors is expected to make a valuable contribution to the understanding of this class of materials. Fundamental properties such as the symmetry of the SC order parameter or, possibly, excitations due to the SC pairing interaction might be revealed.
This work reports on STM measurements carried out at low temperatures (320 mK) and under UHV conditions. A magnetic field of up to 12 T could be applied to confirm superconductivity of clean samples. For the materials investigated here, spectroscopic features in the order of a few hundred µ eV are expected, calling for an excellent energy resolution during STS. The sufficiently high resolution of our STM has been verified by resolving the sub-meV SC energy gap of aluminum. Clean sample surfaces were prepared by in situ cleaving of the single crystals. Preliminary STS measurements were conducted on single crystalline samples of the HF superconductors CeCoIn5 and CeCu2Si2.