Spin Resonance in the New-Structure-Type Iron-Based Superconductor CaKFe4As4

Abstract

The dynamical spin susceptibility in the new-structure-type iron-based superconductor CaKFe${}_4$As${}_4$ was investigated by using a combination of inelastic neutron scattering (INS) measurements and random phase approximation (RPA) calculations. Powder INS measurements show that the spin resonance at $Q_{\text{res}}=1.17(1)$~${\text{A˚}}^{-1}$, corresponding to the $(\pi ,\pi )$ nesting wave vector in tetragonal notation, evolves below $T_{\text{c}}$. The characteristic energy of the spin resonance $E_{\text{res}}=12.5$~meV is smaller than twice the size of the superconducting gap ($2\Delta$). The broad energy feature of the dynamical susceptibility of the spin resonance can be explained by the RPA calculations, in which the different superconducting gaps on different Fermi surfaces are taken into account. Our INS and PRA studies demonstrate that the superconducting pairing nature in CaKFe${}_4$As${}_4$ is the $s_{\pm }$ symmetry.

http://journals.jps.jp/doi/10.7566/JPSJ.86.093703

References in corpus (15)

• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• High-temperature superconductivity in iron-based materials
• LiFeAs: An Intrinsic FeAs-based Superconductor with Tc = 18K
• Effect of Structural Parameters on Superconductivity in Fluorine-Free LnFeAsO1-y (Ln=La,Nd)
• Superconductivity and Crystal Structures of (Ba1-xKx)Fe2As2 (x = 0 - 1)
• Lattice and magnetic instabilities in CaFe2As2: A single crystal neutron diffraction study
• Theory of magnetic excitations in iron-based layered superconductors
• Magnetism in Fe-based superconductors
• Neutron scattering as a probe of the Fe-pnicitide superconducting gap
• Superconductivity in KCa${}_2$Fe${}_4$As${}_4$F${}_2$ with Separate Double Fe${}_2$As${}_2$ Layers
• Spin fluctuations in LiFeAs observed by neutron scattering
• Strong $(\pi ,0)$ spin fluctuations in $\beta$-FeSe observed by neutron spectroscopy
• Inelastic neutron scattering study on the resonance mode in an optimally doped superconductor LaFeAsO${}_{0.92}$F${}_{0.08}$
• Spin resonance in the superconducting state of Li${}_{1-x}$Fe${}_x$ODFe${}_{1-y}$Se observed by neutron spectroscopy
• Spin resonance peak in Fe-based superconductors with unequal gaps

Cited by in corpus (1)

• Electronic properties, low-energy Hamiltonian and superconducting instabilities in CaKFe${}_4$As${}_4$