Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: SC: Iron-Based Superconductors - Theoretical Approaches
TT 17.2: Vortrag
Dienstag, 23. März 2010, 14:15–14:30, H20
Magnetism and pairing symmetries in a three-orbital model for pnictides — •Maria Daghofer1, Andrew Nicholson2,3, Adriana Moreo2,3, and Elbio Dagotto2,3 — 1IFW Dresden, Dresden, Germany — 2University of Tennessee, Knoxville, USA — 3Oak Ridge National Laboratory, USA
While the shape of the Fermi surface (FS) obtained with the local density approximation (LDA) can be reproduced by a two-orbital model, three orbitals are needed to produce the degeneracy of the hole pockets. We discuss a three-orbital model including the xz, yz, and xy orbitals of the iron ions, which qualitatively reproduces the FS shape and orbital composition obtained by LDA calculations for undoped pnictides [1,2]. Since this model is not at half filling, orbital order becomes a possibility in addition to various magnetic phases. Using numerical techniques, we find an antiferromagnetic metal at realistic Coulomb interaction, while orbital order is only induced at at interaction strengths that are probably too strong to be realistic for pnictides. We also investigate possible pairing operators allowed by the lattice symmetry. We find that almost all of them lead to intra- as well as inter-band pairing, i.e., Cooper pairs that are formed by two electrons coming either from the same or from different bands. We also discuss consequences of inter-band pairing.
[1] A. Moreo, M. Daghofer, A. Nicholson, E. Dagotto, PRB 80, 104507 (2009)
[2] M. Daghofer, A. Nicholson, A. Moreo, and E. Dagotto arXiv:0910.1573