Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: SC: Iron-Based Superconductors - Theoretical Approaches
TT 17.3: Vortrag
Dienstag, 23. März 2010, 14:30–14:45, H20
Spin Density Waves in the Iron Pnictides - Itinerant Magnetic Excitations — •Johannes Knolle1, Ilya Eremin1,2, and Andrey Chubukov3 — 1Max-Planck-Institut für Physik komplexer Systeme, D-01187 Dresden, Germany — 2Institut für Mathematische und Theoretische Physik, TU Braunschweig, D-38106 Braunschweig, Germany — 3Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
We study the spin wave excitations of the parent iron-based superconductors employing the three band model which consists of one hole pocket centered around the Γ-point, and two elliptic electron pockets centered around (π,0) and (0,π) points of the Brillouin zone (BZ), respectively. Without taking ellipticity into account, the spin wave excitations are degenerate at (π,0) and (0,π) points representing the degeneracy of the underlying spin state. The ellipticity removes the degeneracy and selects the required (π,0) or (0,π) state. Simultaneously, it also leaves only one gapless Goldstone mode. We analyze the dispersion of the spin waves along the symmetry points of the first BZ for various strengths of the ellipticity parameter and compare the results with available experimental data. We find that neutron scattering data on the damping of the spin waves and their dispersion can be well described within the itinerant description.