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TT: Fachverband Tiefe Temperaturen

TT 21: Superconductivity: Poster Session

TT 21.23: Poster

Montag, 16. März 2015, 15:00–18:00, Poster B

Ferromagnetic Phase Transition in Li deficient LiFeAs — •Uwe Gräfe¹, Shiv Jee Singh¹, Robert Beck¹, Sabine Wurmehl^{1, 2}, Christian Heß^{1, 3}, and Bernd Büchner^{1, 2, 3} — ¹IFW Dresden, Helmholtzstraße 20, 01069 Dresden — ²TU Dresden Institut für Festkörperphysik, 01062 Dresden — ³Center for Transport and Devices, Technische Universität Dresden, 01069 Dresden, Germany

While other iron pnictides only develop superconductivity under doping with holes or electrons, LiFeAs is a stoichiometric superconductor. So far doping, e.g. electron doping with Co [1] or Ni [2], is supressing the superconducting transition temperature. The same holds true for Li deficiency which formally corresponds to hole doping. This deficiency also leads to a ferromagnetic phase transition, evidenced by, e.g. magnetization and temperature dependent NQR measurements. Interestingly, upon doping LiFeAs with electrons, the NQR frequency at room temperature is shifted to lower values and vice versa for holes, i.e., the NQR frequency can be used as an absolute reference for the carrier doping in the material. Here we present systematic, NQR-controlled studies of the impact of various doping schemes on the structural, magnetic, and transport properties.

[1] Aswartham et al. 2011, PRB 84 054534

[2] Pitcher et al. 2010, JACS 132 10467