Large downward renormalization of spin excitation energies in BaKFeAs due to electron correlation effects

Murai, Naoki  ; Kajimoto, Ryoichi  ; Suzuki, Katsuhiro*; Nakajima, Masamichi*; Ikeda, Hiroaki*; Ideta, Shinichiro*; Tanaka, Kiyohisa*

We report inelastic neutron scattering (INS) study of hole-doped iron-based superconductor BaKFeAs (x = 0.25). The INS data show a spin-wave-like dispersive feature, with a zone boundary energy of 200 meV. A random phase approximation (RPA) treatment of the dynamical spin susceptibility, incorporating the band renormalization factor of 3 derived from angle-resolved photoemission spectroscopy (ARPES) measurements on the same sample, provides a reasonable description of the observed spin excitations. This analysis shows that the Fe-3d bandwidth narrowing due to electron correlation is directly reflected in the spin excitation energy scale. We will discuss the current state of our analysis relating the magnetic response to the underlying electronic structure of the materials.