Evidence for electron-electron correlations in La₂CuO₄ and La_2-xSr_xCuO₄ superconductors

We report a study of the magnetic susceptibility of La2-xSrxCuO4 for x=0, 0.10, 0.15, 0.20 from 4-350K. Our data suggest that La2CuO4 has a spin-density wave or antiferromagnetic transition near 250K. The Sr doped superconductors have a Pauli susceptibility above Tc=35-40K that is enhanced by electron-electron correlations. The variation in Tc with Sr doping is not directly correlated with the change in electron density of states. © 1987.