Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 68: Superconductivity: Fe-based Superconductors - Theory I

TT 68.9: Talk

Wednesday, April 2, 2014, 17:30–17:45, HSZ 201

Topological Surface States in Paramagnetic, Antiferromagnetic, and Superconducting Iron Pnictides — •Alexander Lau — Institute of Theoretical Physics, Technische Universität Dresden, Dresden, Germany

Motivated by the topologically nontrivial electronic structure of iron pnictides, we study surface states in various strip geometries. For the paramagnetic phase, the existence of these states can be understood from a topological argument. If we go to the antiferromagnetic phase, the surface bands split, depending on the geometry of the strip. In the superconducting phase, assuming an s_±-wave gap structure, the topological surface states under certain conditions remain in the gap. Interestingly, they exist side by side with Andreev bound states for small superconducting gaps and even merge with them for increasing gap amplitude. The bulk and surface dispersions are obtained from exact diagonalisation of two- and five-orbital models.