LOCAL STRUCTURAL AND ELECTRONIC CHANGES ACCOMPANYING PHOTODOPING IN YBA2CU3O6-X

Polarized X-ray absorption measurements reveal that photodoping of oxy gen deficient YBa2Cu3O6+x (YBCO) produces a local axial distortion of the CuOx chains. The broad normal state axial Cu(1)-O(4) bond distribu tion becomes two well-defined peaks in the photodoped state and sugges t local ordering. XANES measurements reveal a transfer of hole density into the CuO2 planes. These results support a common structure-relate d transport enhancement mechanism in chemically doped and photodoped h igh temperature superconductor systems. (C) 1997 Elsevier Science B.V.