POSITRON-ANNIHILATION STUDY OF SR DOPING IN LA2-XSRXCUO4

We present a combined experimental and theoretical study of the effect s of Sr doping on the electronic structure of La2-xSrxCuO4. Electron-p ositron momentum distributions have been measured to high statistical precision (> 4 x 10(8) counts) at room temperature for samples with Sr concentrations of x = 0.0, 0.1, 0.13 and 0.2. Analysis of all four sp ectra reveal strong features due to electron-positron wavefunction ove rlap, in quantitative agreement with theoretical calculations. The Sr doped samples show discontinuities consistent with the presence of a F ermi surface. The form and position of these features are in general a greement with the predictions of band theory. Correspondence between t heory and experiment, as well as some differences, are revealed by a d etailed study of the changes in electron-positron momentum density wit h increasing Sr doping.