Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 17: Superconductivity: Fe-based Superconductors - 122 Part 2 & Theory

TT 17.9: Talk

Tuesday, March 27, 2012, 11:45–12:00, H 2053

Competing antiferromagnetic states in the pnictides — •Philip M. R. Brydon, Jacob Schmiedt, and Carsten Timm — Technische Universität Dresden, Dresden, Germany

Motivated by the complicated nesting properties of the Fermi surface [1], we present a study of the magnetic order in the pnictides focusing upon the competition of the observed stripe order with other commensurate and incommensurate states. Starting from a phenomenological microscopic model, we derive the mean-field Ginzburg-Landau free energy, and systematically construct the magnetic phase diagram as a function of the doping and key band structure parameters [2]. We show that the number, location, and relative size of the hole pockets crucially controls the magnetic state, which we explain in terms of the competition between different nesting instabilities. We discuss the implications for electronic-only models of the magnetic order.
J. Schmiedt, P. M. R. Brydon, and C. Timm, arXiv:1108.5296 (unpublished).
P. M. R. Brydon, J. Schmiedt, and C. Timm, arXiv:1109.2071 (accepted for publication in Phys. Rev. B).