Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 5: Superconductivity: Fe-based Superconductors - FeSe and 122
TT 5.4: Vortrag
Montag, 1. April 2019, 10:15–10:30, H23
Impact of magnetic disorder and van der Waals interaction on structure parameters of FeSe and FeTe superconductors by density functional theory calculations — •Felix Lochner1,2, Ilya Eremin2, Tilmann Hickel1, and Jörg Neugebauer1 — 1Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany — 2Theoretische Physik III, Ruhr-Universität Bochum, Bochum, Germany
Density functional theory (DFT) calculations for iron base superconductors often show deviations in the lattice constants compared to experiment. Therefore, we have studied the impact of the magnetic phase on the lattice parameters of FeSe and FeTe. We focus on the competition between stripe-type anti ferromagnetism (AFM) and paramagnetic disorder (PM). The PM state is implemented by using the spin-space average approach [1]. We find for both magnetic states an unphysical behavior of the structural ground state. The reason is the lack of Van der Waals (vdW) interaction in the employed PBE-GGA functional. Therefore, we have applied several approaches to include vdW. Our results show, that the additional vdW forces have a large impact on the out-of-plane lattice constant. Using the PM spin configuration together with the Van der Waals corrections we obtain lattice constants that are in excellent agreement with those obtained from experiment [2].
F. Körmann, A. Dick, B. Grabowski, T. Hickel, and J. Neugebauer, Phys. Rev. B 85, 125104 (2012)
F. Ricci and G. Profetta, Phys. Rev. B 87, 184105 (2013)