Evidence for Electron-Electron Correlations in Pure and Sr-Doped La₂CuO₄

SQUID susceptibility measurements on La2CuO4 and La2-xSrxCuO4 provide evidence for electron-electron correlations. Our data suggest that La2CuO4 has a spin-density wave (or antiferromagnetic) transition near 250 K. The Sr doped superconductors have a Pauli susceptibility in the normal state that is enhanced by electron-electron correlations. The variation in the superconducting Tc with Sr doping is not directly correlated with the change in electron density of states. © 1987 The Japan Society of Applied Physics.