Magnetic properties of the overdoped superconductor LaSrCuO with and without Zn impurities

Wakimoto, Shuichi  ; Birgeneau, R. J.*; Kagedan, A.*; Kim, H.-K.*; Swainson, I.*; Yamada, Kazuyoshi*; Zhang, H.*

The magnetic properties of the Zn-substituted overdoped high- superconductor LaSrCuO (LSCO) have been studied by magnetization measurements and neutron scattering. Magnetization measurements reveal that for Zn-free samples with a Curie term is induced implying the existence of local paramagnetic moments. A comparison of the Curie behaviour between Zn-doped and Zn-free samples signifies a general competitive relationship between the superconductivity and the induced paramagnetic moment. Neutron scattering measurements show that Zn-substitution in overdoped LSCO anomalously enhances the inelastic magnetic scattering spectra around the position, peaking at meV. These facts are discussed on the basis of a "swiss-cheese" model of Zn-substituted systems as well as a microscopic phase separation scenario in the overdoped region indicated by muon-spin-relaxation measurements.