Electronic properties of YBa 2Cu 3O 7− δ and Bi 2Sr 2CaCu 2O 8 superconductors studied by Compton scattering technique

Abstract

The temperature dependence and the anisotropy of the electron momentum distribution of high temperature superconductors YBa 2Cu 3O 7− δ and Bi 2Sr 2CaCu 2O 8 have been studied using Compton scattering of high energy X-rays from a synchrotron source. Both high resolution (0.16 a.u. of momentum) and low resolution (0.60 a.u.) spectrometers were used. Polycrystalline and single crystal samples were measured below and above the transition temperature. No temperature effect in the Compton profiles was found contrary to an earlier report. The electron momentum anisotropy and its temperature dependence were also measured between the c-axis and the basal plane. The anisotropy in the YBCO Compton profile is consistent with recent band calculations: larger effects are obtained in BSCCO.