BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:Andreev Reflection Spectroscopy of the Pure and Cd-doped Heavy Fer mion Superconductor CeCoIn5: Detecting Order Parameter Symmetry and Compe ting Phases - Laura H. Greene\, Department of Physics and the Frederick Se itz Materials Research Laboratory\, University of Illinois at Urbana-Champ aign DTSTART:20060920T101500Z DTEND:20060920T111500Z UID:TALK5252@talks.cam.ac.uk CONTACT:Michael Sutherland DESCRIPTION:Andreev reflection spectroscopy results are obtained with nano scale normal-metal Au tips on single crystals of the pure and Cd-doped hea vy-fermion superconductor CeCoIn5. Contacts are shown to be in the Sharvi n (ballistic) limit. Asymmetry observed in the background conductance star ting at T* (the heavy-Fermion condensation temperature) increasing with de creasing temperature to Tc (the superconducting condensation temperature)\ , signifies the emerging heavy-fermion liquid. Below Tc\, the enhancemen t of the sub-gap conductance arises from Andreev reflection. According to standard theory\, the Fermi velocity mismatch between these materials sho uld yield no Andreev reflection. The signal we do observe is several times weaker than that observed in conventional superconductors\, but consisten t with other heavy-fermion superconductor data reported. Data taken in th e (001)\, (110) and (100) orientations provide consistent and reliable spe ctroscopic evidence of a dx2-y2 superconducting order parameter. Measureme nts on Cd-doped CeCoIn5\, at the 10% doping level\, show characteristics c onsistent with antiferromagnetic and subsequent superconducting transition s with decreasing temperature. The roles of competing phases in this mate rial will be discussed.\n\nThis work is in collaboration with Wan Kyu Park \, J. L. Sarrao\, J. N. Thompson\, L. Pham\, T. Park\, S. Maquilon and Z. Fisk. \n\n LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics END:VEVENT END:VCALENDAR