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TT: Fachverband Tiefe Temperaturen

TT 27: SC: Fe-based Superconductors - LiFeAs

TT 27.1: Talk

Tuesday, March 15, 2011, 14:00–14:15, HSZ 304

Nuclear Magnetic Resonance study of pure and Ni/Co doped LiFeAs — •Hans-Joachim Grafe, Seung-Ho Baek, Franziska Hammerath, Uwe Gräfe, Yannic Utz, Luminita Harnagea, Claudia Nacke, Saicharan Aswartham, Sabine Wurmehl, and Bernd Büchner — Leibniz-Institut für Festkörper- und Werkstoffforschung, Dresden, Germany

We present Nuclear Magnetic and Nuclear Quadrupole Resonance (NMR/NQR) measurements on pure, Ni and Co doped LiFeAs single crystals. The parent compound LiFeAs exhibits unconventional superconductivity with a transition temperature of about 17 K. Unlike other Fe based superconductors, where superconductivity is induced or stabilized by Co or Ni doping, replacement of Fe by these elements leads to a suppression of the superconducting transition temperature in LiFeAs. In case of Ni doping, a bulk magnetic order is induced below about 160 K. In contrast, for Co doping, the superconducting transition temperature is only reduced, but no magnetic order is observed. We discuss the nature and the origin of this magnetic order and its relation to unconventional superconductivity in pure LiFeAs.