Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 40: Superconductivity: Ferropnictides 1
TT 40.9: Vortrag
Donnerstag, 26. März 2009, 16:15–16:30, HSZ 03
Doping dependence of the charge distribution of iron pnictides — •Guillaume Lang1, Hans-Joachim Grafe1, Katarina Manthey1, Franziska Hammerath1, Dalibor Paar1,2, Katrin Koch3, Helge Rosner3, Günther Behr1, Jochen Werner1, and Bernd Büchner1 — 1IFW Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany — 2Dept. of Physics, Fac. of Science, Univ. of Zagreb, P. O. Box 331, HR-10002 Zagreb, Croatia — 3Max Planck Inst. for Chem. Phys. of Solids, Nöthnitzer Str. 40, D-01187 Dresden, Germany
We have investigated the evolution, on doping, of the charge distribution in the new LaO1−xFxFeAs superconductor. This is done using 75As Nuclear Quadrupole Resonance (NQR), which is a sensitive local probe of the electric field gradient generated by the charge distribution. A significant increase of the quadrupole frequency is observed when going from the undoped situation to the superconducting region of the phase diagram, reflecting the change in density or spatial distribution of the electrons ([1], and subsequent measurements to be published). This increase cannot be properly accounted for by LDA calculations, even though there is good agreement between theory and experience for the undoped case. We discuss this discrepancy as well as the relation to the superconductivity, i.e., the link to the doping-dependence of the critical temperature.
[1] H.-J. Grafe, G. Lang et al., arXiv:0811.4508, submitted to New Journal of Physics (invited paper, special issue on iron pnictides superconductors)