Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 39: SC: Iron-Based Superconductors - 1111
TT 39.1: Vortrag
Freitag, 26. März 2010, 10:15–10:30, H19
Insight, puzzles, and problems into the physics of Fe-pnictides from optics — •S.-L. Drechsler1, H. Rosner2, R. Schuster1, F. Roth1, M. Grobosch1, M. Rotter3, K. Koepernik1, D. Singh4, L. Zhang4, D. Jorendt3, N. Wizent2, G. Behr1, J. van den Brink1, N.L. Wang5, B. Buechner1, and M. Knupfer1 — 1Inst. f. Festkörper- & Werkstoffforsch., Dresden — 2Max-Planck-Inst. f. Chem. Physik fester Stoffe, Dresden — 3Department Chemie & Biochemie, Ludwig-Maximillians Universität München, München — 4Oak Ridge Nat. Lab., Oak Ridge, Tennessee, USA — 5Beijing Nat. Lab., f. Cond. Mat. Phys. Inst. of Phys., Chin. Acad. of Sci., Beijing, China
We report Drude plasma frequencies (PF) for 12 Fe-pnictides from density functional theory (DFT) based calculations and compare them with experimental PF from reflectivity. The observed renormalization points to moderate many-body effects beyond the DFT like in ordinary transition metals. From large empirical background dielectric constants ε∞ ∼10 , we estimate strong As and P polarizabilities which significantly reduce the Hubbard Ud from about 4 eV as suggested by significantly correlated [1] "bad metal" scenarios to below 2 eV pointing to rather strong polaronic effects [2]. We compare the dielectric and loss functions calculated within the RPA employing the DFT band structure for the parent compounds LaOFeAs and LaOFeP with single crystal derived data [1] and determine the frequency region with the strongest many-body effects beyond the RPA.
[1] M.M. Qazilbash et al. Nature Phys. 5, (2009) 647.
[2] G. Sawatzky et al. Europhys. Lett. 86 (2009) 17006.