High Tc superconductivity in CaKFe${}_4$As${}_4$ in absence of nematic fluctuations

Abstract

We employ polarization-resolved Raman spectroscopy to study multi-band stoichiometric superconductor CaKFe${}_4$As${}_4$. The B${}_{2g}$ symmetry Raman response shows no signatures of Pomeranchuk-like electronic nematic fluctuations which is observed for many other Fe-based superconductors. In the superconducting state, we identify three pair-breaking peaks at 13.8, 16.9 and 21 meV and full spectral weight suppression at low energies. The pair-breaking peak energies in Raman response are about 20% lower than twice the gap energies as measured by single-particle spectroscopy, implying a sub-dominant $d$-wave symmetry interaction. We analyze the superconductivity induced phonon self-energy effects and give an estimation of weak electron-phonon coupling constant ${\lambda }^{\Gamma }$=0.0015.

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Cited by in corpus (9)

• Competing pairing interactions responsible for the large upper critical field in a stoichiometric iron-based superconductor, CaKFe${}_4$As${}_4$
• Charge Density Wave order and electron-phonon coupling in ternary superconductor Bi${}_2$Rh${}_3$Se${}_2$
• Ultrafast Optical Spectroscopy Evidence of Pseudogap and Electron-Phonon Coupling in an Iron-Based Superconductor KCa${}_2$Fe${}_4$As${}_4$F${}_2$
• Elastoresistance measurements on CaKFe${}_4$As${}_4$ and KCa${}_2$Fe${}_4$As${}_4$F${}_2$ with the Fe site of $C_{2v}$ symmetry
• Preferred Spin Excitations in the Bilayer Iron-Based Superconductor CaK(Fe${}_{0.96}$Ni${}_{0.04}$)${}_4$As${}_4$ with Spin-Vortex Crystal Order
• Fluctuations and pairing in Fe-based superconductors: Light scattering experiments
• Quadrupolar charge dynamics in the nonmagnetic FeSe${}_{1-x}$S${}_x$ superconductors
• Superconductivity and phonon self-energy effects in Fe${}_{1+y}$Te${}_{0.6}$Se${}_{0.4}$
• Anisotropic superconductivity and Fermi surface reconstruction in the spin-vortex antiferromagnetic superconductor CaK(Fe${}_{0.95}$Ni${}_{0.05}$)${}_4$As${}_4$