Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 23: Superconductivity: Fe-based Superconductors - 1111
TT 23.4: Vortrag
Montag, 11. März 2013, 17:30–17:45, H21
Carrier doping by current injection into LaOFFeAs — •Irina Lazareva1, Yury Koval1, Christian Steiner1, Sabine Wurmehl2, Bernd Büchner2, Tobias Stürzer3, Dirk Johrendt3, and Paul Müller1 — 1Department of Physics, Universität Erlangen, Detschland — 2IFW Dresden, Deutschland — 3Department Chemie, LMU München, Detschland
Recently, we were able to change the carrier concentration of hole-doped high-Tc superconductors by injection of large currents along the c-axis. We extend this type of experiments to electron-doped pnictides. From our earlier interpretation we should expect that trapping of electrons caused by current injection would decrease the available carrier concentration. Indeed, by various experiments with superconductors from the LaO1−xFxFeAs family we are able to show that trapped electrons caused by current injection perpendicular to the FeAs planes decrease the carrier concentration. We present a spectacular confirmation of this interpretation by the Tc increase by more than 15 K in heavily overdoped LaO.74F0.26FeAs. We performed similar experiments with the recently discovered 1048 layered pnictides of the composition Ca10(FeAs)10(Pt4As8) [1]. The general tendency of carrier doping by trapped electrons was confirmed. A rather interesting discovery was the evolution of hysteretic c-axis IV-characteristics. This is a strong indication of intrinsic Josephson effects. We discuss these results in terms of a change of anisotropy by carrier doping.
[1] T. Stürzer, G. Derondeau, D. Johrendt, Phys. Rev. B 86, 060516(R) (2012).