Magnetic excitations in highly hole-doped layered nickel oxides studied by inelastic neutron scattering

Kajimoto, Ryoichi  ; Fujita, Masaki*; Nakajima, Kenji  ; Iida, Kazuki*

Layered perovskite nickel oxide LaSrNiO has been famous in that holes doped in the NiO planes by the Sr substitution induces so-called stripe orderings of charges and spins at 1/2. On the other hand, the highly hole-doped region of 1/2 is another interesting arena of research attracting much attention recently: the electric conductivity gradually increases as increases, and finally becomes metallic at 1. Nevertheless, the checkerboard charge correlation persists, which results in an anomalous metallic state with pseudo gap at . Moreover, the gradual change of the orbital character of Ni ions is suggested. These unique physical properties are expected to affect the spin correlations. Accordingly, we performed inelastic neutron scattering measurements of = 0.5 and 0.9 samples to investigate their spin dynamics. In the presentation, we compare the magnetic excitations in both the samples in more detail.