Momentum density and Fermi surface of Nd 22xCe xCuO 42d

High-temperature positron two-dimensional angular correlation of annihilation radiation ~2D-ACAR! measurements have recently been succesfully applied to map parts of the Fermi surface of YBa2Cu3O72d . Using the same principle, we have been able to observe with a bulk sensitive method, the Fermi surface of Nd22xCe xCuO42d . Although positron trapping by defects and correlation effects are strong, positron 2DACAR measurements provide a signal from the Fermi surface which agrees with band-structure calculations, confirming earlier surface sensitive photoemission experiments.