Evidence for anisotropic atomic displacements and orbital distribution in the inhomogeneous CuO2 plane of the Bi2Sr2CaCu2O8+δ system Original Research Article

We have used a combination of the Cu K-edge extended X-ray absorption fine structure (EXAFS), and the Cu L-edge X-ray absorption measurements, with polarization vector parallel to the two orthogonal Cu–O–Cu bonds, to explore the directional instantaneous atomic displacements and the orbital distribution within the heterogeneaous CuO2 plane of the Bi2Sr2CaCu2O8+δ (Bi2212) system. The results show an anisotropic Cu–O bond distribution, measured by the EXAFS in the two directions, and reveal large anisotropy of the unoccupied Cu 3d orbitals. The outcome of the present measurements is consistent with the nanoscale heterogeneities with coexisting electronic components.