抄録
Neutron scattering experiments have been performed to study spin excitations in the overdoped La2-xSrxCuO4 (0.25≤x≤0.30) using triple-axis and time-of-flight techniques. Low energy magnetic excitations (ω<10 meV) show incommensurate peaks for the superconducting samples with a maximum at-6 meV in the energy spectrum. As doping increases, the maximum of the dynamic susceptibility X″(ω) decreases linearly with Tc and, finally, the low energy excitations become unobservable at x=0.30 coincidentally with the disappearance of bulk superconductivity. Magnetic excitation spectra in the intermediate energy range (20<ω<100meV) are found to decrease monotonically with doping. These observations are discussed in terms of a phase separation of the system into a remnant magnetic region, which possibly consists of a stripe structure and supports the superconductivity, and a non-magnetic metallic region.
