Dresden 2011 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 1: TR: Graphene 1 (jointly with MA, HL, and DY)

TT 1.6: Vortrag

Montag, 14. März 2011, 12:15–12:30, HSZ 03

Evidence for Josephson-coupled superconducting regions at the interfaces of highly oriented pyrolytic graphite — •Ana Ballestar, Jose Barzola-Quiquia, and Pablo Esquinazi — Abteilung für Supraleitung und Magnetismus, Institut für Experimentelle Physik II, Universität Leipzig, Linnéstrasse 5, 04103 Leipzig, Germany

The first observation of superconductivity in doped graphite goes back to 1965 when it was observed in the potassium graphite intercalated compound C8K. A considerable amount of studies had reported this phenomenon in intercalated graphite compounds or doped graphite, however the superconducting properties of pure graphite are still under discussion. Indirect evidences for superconductivity at graphite interfaces have been recently published. In order to better understand these interfaces properties, we prepared micro structured samples (Lamellas) from pure highly oriented pyrolitic graphite. By reducing the dimension in the in plane configuration to ∼ 200 nm we can measure the electrical response of graphite interfaces. We obtained evidence for the existence of Josephson-coupled quasi two dimensional superconducting regions. Temperature dependence of the voltage, as well as I(V) characteristic curves indicate that superconductivity exists even above 150 K. The results support the view that HOPG is a system with interfaces containing non-percolative superconducting domains immersed in a semiconducting graphene-based matrix.