Subdominant $d$-wave interaction in superconducting CaKFe$_4$As$_2$?
| Autor: | Jost, Daniel, Scholz, Jan-Robin, Zweck, Ulrike, Meier, William R., Böhmer, Anna E., Canfield, Paul C., Lazarević, Nenad, Hackl, Rudi |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 98, 020504 (2018) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.98.020504 |
| Popis: | We report inelastic light scattering results on the stoichiometric and fully ordered superconductor CaKFe$_4$As$_2$ as a function of temperature and light polarization. In the energy range between 10 and 315 cm$^{-1}$ (1.24 and 39.1 meV) we observe the particle-hole continuum above and below the superconducting transition temperature $T_c$ and 7 of the 8 Raman active phonons. The main focus is placed on the analysis of the electronic excitations. Below $T_c$ all three symmetries projected with in-plane polarizations display a redistribution of spectral weight characteristic for superconductivity. The energies of the pair-breaking peaks in $A_{1g}$ and $B_{2g}$ symmetry are in approximate agreement with the results from photoemission studies. In $B_{1g}$ symmetry the difference between normal and superconducting state is most pronounced, and the feature is shifted downwards with respect to those in $A_{1g}$ and $B_{2g}$ symmetry. The maximum peaking at 134 cm$^{-1}$ (16.6 meV) has a substructure on the high-energy side. We interpret the peak at 134 cm$^{-1}$ in terms of a collective Bardasis-Schrieffer (BS) mode and the substructure as a remainder of the pair-breaking feature on the electron bands. There is a very weak peak at 50 cm$^{-1}$ (6.2 meV) which is tentatively assigned to another BS mode. Comment: 8 pages, 9 figures |
| Databáze: | arXiv |
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