Low-energy spin excitation in lightly-doped Bi2.4Sr1.6CuO6+δ studied by inelastic neutron-scattering experiment

Low-energy spin excitation below 10meV in non-superconducting lightly-doped Bi2+xSr2-xCuO6+δ(BSCO)x=0.4 was studied by neutron-scattering measurement. We observed a broad single peak centered at (0.5,0.5) reciprocal position in tetragonal notation. The intensity is enhanced with increasing the temperature, and weakens at the equivalent magnetic position with larger Q. These results indicates that the observed signal is intrinsic spin excitation spectrum, and therefore, we have clarified the existence of spin excitation in the BSCO system for the first time.