Fe-impurity-induced magnetic excitations in heavily over-doped LaSrCuFeO

Ikeuchi, Kazuhiko*; Kikuchi, Tatsuya*  ; Nakajima, Kenji  ; Kajimoto, Ryoichi  ; Wakimoto, Shuichi  ; Fujita, Masaki*

Inelastic neutron scattering experiments were performed to investigate the effect of Fe substitution on the magnetic excitation spectra in a heavily hole-doped cuprate system LaSrCuFeO. Well-defined low-energy magnetic excitations, associated with a static magnetic order, were observed at the incommensurate (IC) positions. The incommensurability of 0.144 (r.l.u) was larger than that of 0.125 (r.l.u) in LSCO with = 0.25, suggesting an increase of incommensurability by Fe substitution. In addition to the obvious effect on IC excitations, we show the emergence of ring-shaped magnetic excitations by Fe-substitution. These results are incompatible with a simple pinning scenario of the stripe order, which is characterized by local spin correlations. The metallic aspect of the low-energy part of the magnetic excitation, which underlies high-temperature superconductivity in over-doped cuprate systems, would be enhanced/induced by Fe substitution.