  Charge redistribution in high-Tc superconductors due to structural defects or
interfaces is known to be crucial for electronic applications as the band
structure is modified on a local scale. In order to investigate these effects
in more detail, we address the normal-state properties of YBa2Cu3O7 (YBCO) in
the vicinity of YBCO-metal interfaces by electronic structure calculations for
well relaxed interface configurations. Our findings can be interpreted in terms
of a band-bending mechanism complemented by local screening effects. We derive
quantitative results for the intrinsic doping of the superconducting CuO2
planes due to the metal interface. In particular, the net charge transfer
amounts to 0.13 electrons in favour of each intraplane copper site, which
appears to be a typical value for interfaces of high-Tc superconductors, thus
opening great possibilities for a systematic optimization of wires and tapes
from high-Tc materials.
