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TT: Fachverband Tiefe Temperaturen

TT 10: Poster Session: Superconductivity

TT 10.15: Poster

Montag, 14. März 2011, 14:00–18:00, P4

⁷⁵As NMR study on (Eu/Sr)(Fe/Co)₂As₂ single crystal. — •Rajib Sarkar¹, Panchanana Khuntia¹, Michael Baenitz¹, Ramesh Nath³, Hirale Jeevan², Philipp Gegenwart², and Frank Steglich¹ — ¹MPI for Chemical Physics of Solids, 01187 Dresden, Germany — ²I. Physik. Institut, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany — ³IISER-TVM, Trivandrum-695016, India

The AFe₂As₂ (122)(A= Sr, Ba, Ca Eu) systems is the focus of research interest because of high temperature superconductivity (SC) with T_c‘s up to =38 K. The EuFe₂As₂ compound is special because of highest Fe SDW transition of T_sdw=190 K among the pnictides [1]. In addition at T_N=19 K antiferromagnetic order of Eu²⁺ shows up. Moreover Eu²⁺ is magnetic with S=7/2, while Ba²⁺, Sr²⁺ and Ca²⁺ are nonmagnetic ions [2]. Interestingly, the Fe SDW is completely suppressed in Eu_0.5K_0.5Fe₂As₂ and SC is found below T_c=32 K. However unlike the other 122 system SC could not be achieved only by substitution of Co²⁺ at the Fe site, may be due to the Eu²⁺ AFM ordering. Nevertheless with the 80% Sr doping at the Eu²⁺ site and the optimal doping of Co at the Fe site, one can get the SC with T_c=20 K[3,4]. Being a local probe, NMR is a very useful tool to study the microscopic properties of these Fe-pnictides. Here we report the ⁷⁵As field sweep NMR investigations superconducting (Eu/Sr)(Fe/Co)₂As₂ single crystals.
Phys. Rev. B 78, 092406 (2008).
Phys. Rev. B 82, 054525 (2010).
J. Phys.: Condens. Matter 22 (2010) 235701.
Sarkar et. al. to be published.