Paramagnon excitations’ theory for resonant inelastic X-ray scattering in doped plane copper oxide superconductors

•Paramagnon excitations are the elementary excitations in doped copper oxide superconductors.•Resonant inelastic X-ray scattering (RIXS) data analysis depends on paramagnon damping.•The evolution of spin excitation spectrum as obtained by RIXS is explained.•RIXS data analysis depends on particular expression for dynamic spin susceptibility.

A relaxation function theory with paramagnon excitations for doped S=1/2S=1/2 two-dimensional Heisenberg antiferromagnetic system in the paramagnetic state is given in view of magnetic response of high-Tc copper oxide superconductors as obtained by resonant inelastic X-ray scattering (RIXS). The results of the theory on Nd(La)–Ba(Sr)–Cu–O and Y–Ba–Cu–O family compounds give fair agreement without especially adjusted parameters to RIXS data. It is shown that RIXS data analysis depends on paramagnon damping and thus affected by approximations made for dynamic spin susceptibility.