J. Phys. IV France 118 (2004) 333-341
DOI: 10.1051/jp4:2004118039

X-ray scattering evidence of a new short range order or correlation in the high Tc superconductor Bi₂Sr₂CaCu₂O

S. Megtert¹, J. Avila², M. Izquierdo², P.A. Albouy³, G. Gu⁴, M.C. Asensio² and R. Comes<sup>1

1</sup>  Laboratoire pour l'Utilisation du Rayonnement Électromagnétique (LURE), Bât. 209D, U.P.S. 91898 Orsay, France
²  Instituto de Ciencia de Materiales de Madrid, CsiC, Cantoblanco, 28049 Madrid, Spain
³  Laboratoire de Physique des Solides, Bât. 510, U.P.S. 91898 Orsay, France
⁴  Physics Department, Brookhaven National Geographic, USA

Abstract
Synchrotron X-ray diffuse scattering experiments performed on a single domain optimally doped crystal of Bi₂Sr₂CaCu₂O ( K) have revealed a new displacive short range order corresponding to a local doubling of the unit cell along the orthorhombic a direction, thus perpendicular to the commonly reported q = 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 Å 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.

© EDP Sciences 2004