ELECTRON-POSITRON MOMENTUM DENSITY IN TL2BA2CUO6

We present calculations of the electron-positron momentum density for the high-T(c) superconductor Tl2Ba2CuO6, together with some preliminary two-dimensional angular correlation of the annihilation radiation (2D-ACAR) measurements. The calculations are based on the first-principles electronic structure obtained using the full-potential linearized augmented plane wave (FLAPW) and the linear muffin-tin orbital (LMTO) methods. We also use a linear combination of the atomic orbitals-molecular orbital method (LCAO-MO) to discuss orbital contributions to the anisotropies. Some agreement between calculated and measured 2D-ACAR anisotropies encourage sample improvement for further Fermi surface investigations. Indeed, our results indicate a non-negligible overlap of the positron wave function with the CuO2 plane electrons. Therefore, this compound may be well suited for investigating the relevant CuO2 Fermi surface by 2D-ACAR.