Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 27: Superconductivity: Fe-based Superconductors - 122

TT 27.3: Vortrag

Dienstag, 12. März 2013, 10:15–10:30, H18

Crystal growth and physical properties of Na-doped BaFe₂As₂ superconducting single crystals — •S. Aswartham¹, M. Abdel-Hafiez¹, D. Bombor¹, A. U. B. Wolter¹, M. Kumar¹, C. Hess¹, D. V. Evtushinsky¹, V. B. Zabolotnyy¹, A. A. Kordyuk¹, T. K. Kim^1,2, S. V. Borisenko¹, S. Wurmehl¹, and B. Büchner¹ — ¹Leibniz Institute for Solid State and Materials Research, D 01069 Dresden, Germany — ²Diamond Light Source Ltd., Didcot OX11 0DE, United Kingdom

Single crystals of Ba_1−xNa_xFe₂As₂ with x = 0, 0.25, 0.35, 0.4 were grown using a self-flux high temperature solution growth technique. The superconducting and normal state properties were studied by temperature dependent magnetic susceptibility, electrical resistivity and specific heat revealing that the magnetic and structural transition is rapidly suppressed upon Na-substitution at the Ba-site in BaFe₂As₂, giving rise to superconductivity. A superconducting transition as high as 34 K is reached for a Na-content of x=0.4. The positive Hall coefficient confirms that the substitution of Ba by Na results in hole-doping similarly to the substitution of Ba by K. Angle resolved photoemission spectroscopy was performed on all Ba_1−xNa_xFe₂As₂ crystals. The Fermi surface of hole-doped Ba_1−xNa_xFe₂As₂ is to high extent the same as the Fermi surface found for the K-doped sister compounds, suggesting a similar impact of the substitution of Ba by either K or Na on the electronic band dispersion at the Fermi level.