Influence of doping on the electronic structure of (La, Sr)2CuO4

High-statistics (>4 x 108 counts), room-temperature measurements of the electron positron momentum density of La2-xSrxCuO4 have been performed for samples with Sr concentrations of x = 0.0, 0.1, 0.13, and 0.2. These spectra have been analyzed in conjunction with theoretical calculations of the electron positron momentum density. The metallic samples show features consistent with the presence of a Fermi surface, but its evolution with increasing Sr concentration does not follow the predictions of band theory. These results may indicate the effects of electron-electron correlation on the electron momentum distribution in the Cu-O plane. 12 refs., 2 figs