Charge redistribution at y Ba2 Cu3 O7 -metal interfaces

Charge redistribution at interfaces is crucial for electronic applications of high- Tc superconductors, since the band structure is modified on a local scale. The authors address the normal-state electronic structure of Y Ba2 Cu3 O7 (YBCO) at an YBCO-metal contact by first principles calculations for prototypical interface configurations. They derive quantitative results for the intrinsic doping of the superconducting Cu O2 planes due to the metal contact. Their findings can be explained in terms of a band-bending mechanism, complemented by local screening effects. The authors determine a net charge transfer of 0.09-0.13 electrons in favor of the intraplane Cu sites, depending on the interface orientation.