Positron 2D-Acar Experiments and Electron-Positron Momentum Density in YBa2Cu307−x

Abstract

ABSTRACTWe discuss positron annihilation (2D-ACAR) measurements in the c-projection on an untwinned metallic single crystal of YBa2Cu3O7-x as a function of temperature, for five temperatures ranging from 30K to 300K. The measured 2D-ACAR intensities are interpreted in terms of the electron-positron momentum density obtained within the KKR-band theory framework. The temperature dependence of the 2D-ACAR spectra is used to extract a ‘background corrected’ experimental spectrum which is in remarkable accord with the corresponding band theory predictions, and displaysin particular clear signatures of the electron ridge Fermi surface.