Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 5: Superconductivity: Fe-based Superconductors - FeSe and 122
TT 5.7: Vortrag
Montag, 1. April 2019, 11:00–11:15, H23
Band engineering in the iron pnictides: Search for topological surface states — •Lars Lauke1, Rolf Heid1, Michael Merz1, Amir-Abbas Haghighirad1, and Jörg Schmalian1,2 — 1Institut für Festkörperphysik, Karlsruher Institut für Technologie (KIT), 76344 Eggenstein-Leopoldshafen, Deutschland — 2Institut für Theorie der Kondensierten Materie, Karlsruher Institut für Technologie (KIT), 76131 Karlsruhe, Deutschland
By band engineering the iron pnictide Fe(SeTe) via ab-initio calculations, we search for topological surface states and realizations of Majorana bound states. Proposed topological states are expected to occur for non-stoichiometric compositions on a surface Dirac cone where issues like disorder scattering and charge transfer between the relevant electronic states have to be addressed. However, this surface Dirac cone is well above the Fermi-level. The goal is to make the surface Dirac cone experimentally accessible by modifying the bulk material without disturbing the surface. Going beyond conventional density functional theory (DFT), we apply the coherent potential approximation (BEB-CPA) in a mixed basis pseudopotential framework to scan the substitutional phase-space of co-substitutions on the Fe- and Se-sites. We find that substitution on the transition-metal-site is not a viable option but a number of viable candidates at the Se-site achiev the desired effect of bringing the Dirac cone into vicinity of the Fermi-level. We further seek to experimentally realize these predicted compounds.