Observation of a neutron spin resonance in the bilayered superconductor CsCa2Fe4As4F2

Journal article

We report inelastic neutron scattering (INS) investigations on the bilayer Fe-based superconductor CsCa2Fe4As4F2 above and below its superconducting transition temperature Tc ≈ 28.9 K to investigate the presence of a neutron spin resonance. This compound crystallises in a body-centred tetragonal lattice containing asymmetric double layers of Fe2As2 separated by insulating CaF2 layers and is known to be highly anisotropic. Our INS study clearly reveals the presence of a neutron spin resonance that exhibits higher intensity at lower momentum transfer (Q) at 5 K compared to 54 K, at an energy of 15 meV. The energy ER of the observed spin resonance is broadly consistent with the relationship ER = 4.9kBTc, but is slightly enhanced compared to the values observed in other Fe-based superconductors. We discuss the nature of the electron pairing symmetry by comparing the value of ER with that deduced from the total superconducting gap value integrated over the Fermi surface.

Authors: Adroja, DT; Blundell, SJ; Lang, F; Luo, H; Wang, Z-C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: Journal of Physics: Condensed Matter
• Volume: 32
• Issue: 43
• Article number: 435603
• Publication date: 2020-08-03
• Acceptance date: 2020-07-03
• DOI: 10.1088/1361-648x/aba28f
• EISSN: 1361-648X
• ISSN: 0953-8984
• Pmid: 32756017
• Language: English
• Keywords: neutron spin resonance; FFR; iron-based superconductors; inelastic neutron scattering