Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 35: Superconductivity: Fe-based Superconductors - 122 and Theory
TT 35.11: Vortrag
Dienstag, 13. März 2018, 12:15–12:30, A 053
Collective modes and short-time dynamics of time-reversal symmetry broken superconductors — •Marvin A. Müller1, Pengtao Shen2, Maxim Dzero2, and Ilya Eremin1 — 1Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44801 Bochum, German — 2Department of Physics, Kent State University, Kent, OH 44242 USA
Motivated by the recent observation of the time-reversal symmetry broken state in K-doped BaFe2As2 systems, we theoretically study the collective modes and the short time dynamics of this state using density-matrix theory on an effective four-band model with two hole and two electron pockets. Hole doping moves the electron bands away from the Fermi surface and leads to frustration between superconducting channels. This results either into s+is or s+id superconductivity, which are both time-reversal symmetry breaking (TRSB) states. Consequently, the Higgs and Leggett modes are coupled and the superconducting ground state accommodates a variety of collective modes. In extremely overdoped systems with incipient electron bands, we find the Higgs mode at ω = 2Δh with an absent Leggett mode similar to a two band model. At dopings before the TRSB occurs and within the TRSB state, we uncover a new coupled collective mode both in the amplitude and in the relative phase of the superconducting gaps. This mode becomes gapless at the boundaries of the TRSB state.