A Comparison of the High-Frequency Magnetic Fluctuations in Insulating   and Superconducting La2-xSrxCuO4
  Inelastic neutron scattering performed at a spallation source is used to make absolute measurements of the dynamic susceptibility of insulating La2CuO4 and superconducting La2-xSrxCuO4 over the energy range 15<EN<350 meV. The effect of Sr doping on the magnetic excitations is to cause a large broadening in wavevector and a substantial change in the spectrum of the local spin fluctuations. Comparison of the two compositions reveals a new energy scale of 22 meV in La1.86Sr0.14CuO4. 
S. M. Hayden (University of Bristol), G. Aeppli (AT&T Bell   Laboratories), H. A. Mook (Oak Ridge National Laboratory), T. G...