X-ray scattering evidence of a new short range order or correlation in the high Tc superconductor Bi2Sr2CaCu2O8+δ

Abstract

Synchrotron X-ray diffuse scattering experiments performed on a single domain optimally doped crystal of Bi 2 Sr 2 CaCu 2 O 8+δ (Tc # 91 °K) have revealed a new displacive short range order corresponding to a local doubling of the unit cell along the orthorhombic a 0 direction, thus perpendicular to the commonly reported q b = 0.21 super-structure modulation. The analysis of the X-Ray diffuse structure shows that it has 2D (Dimensional) character, the planar domains being parallel to the a-b conduction plane with an in plane size of about 60 A at room temperature. Experiments as a function of the temperature (down to 37 K) show that this local order is still present in the superconducting state with no significant change in domain size.