Probing magnons of CaKFe4As4 superconductor

CaKFe4As4 is a hybrid iron superconductor between CaFe2As2 and KFe2As2 that acts like an ordered hole-doped material for the AeFe2As2 (Ae = alkaline earth) parent compound. Unlike hole-doped (Ba1–xKx)Fe2As2 (K-BFA), Ca and K do not occupy crystallographically equivalent sites because of the large differences in their ionic radii. CaKFe4As4 hosts a superconducting (SC) ground state with Tc = 35 K. By transition metal doping, it is possible to tune the phase diagram away from the ideal alkaline earth metal hole doping (K-BFA) and out of the SC dome. By hole-doping with Mn and Cr, the SC is suppressed more quickly than by electron doping with Ni and Co. This resembles the existence or not of SC ground state for these transition metal dopings on the BaFe2As2 parent compound. We wish to study the RIXS spectrum of the parent compound as a function of momentum and compare it to theoretical calculations to motivate the study of magnetism and its interplay with SC on the doped compounds.