Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 8: Superconductivity - Poster Session
TT 8.22: Poster
Monday, March 26, 2007, 14:00–17:45, Poster A
Enhanced superconductivity of Pb nanograins on a biological substrate — •T. Herrmannsdörfer1, O. Ignatchik1, T. P. Papageorgiou1, F. Pobell1, C. Walter1, J. Wosnitza1, C. Hennig2, M. Merroun2, K. Pollmann2, J. Raff2, S. Selenska-Pobell2, and J. von Borany3 — 1Hochfeld-Magnetlabor Dresden (HLD), — 2Institut für Radiochemie, — 3Institut für Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden-Rossendorf, D-01314 Dresden, Germany
Nanogranular materials attract more and more attention due to their exciting physical properties as well as their key role in future technologies. Compared to their bulk counterparts, nanogranular materials can reveal strongly altered properties. As an example, we have demonstrated that the Stoner enhancement factor of the d conduction-electron susceptibility of Pd and Pt nanoclusters is clearly reduced compared to the one of the bulk transition metals. Now we have focused on superconducting properties of lead particles of a well defined single grain size of 19 nm. As for Pd and Pt, these metal nanoclusters have been deposited on a biological template, a purified self-assembling paracrystalline surface layer (S-layer) of Bacillus sphaericus JG-A12 which is composed of identical protein monomers. After a determination of their grain size using x-ray powder diffraction, we have investigated their superconducting B-T phase diagram by means of SQUID magnetometry. The Pb clusters reveal a superconducting critical field of the size of several Tesla which is strongly enhanced compared to the corresponding critical magnetic field of 0.09 T for bulk Pb.