Charge redistribution at YBa2Cu3O7-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. We address the normal-state electronic structure of YBa2Cu3O7 (YBCO) at an YBCO-metal contact by first principles calculations for prototypical interface configurations. We derive quantitative results for the intrinsic doping of the superconducting CuO2 planes due to the metal contact. Our findings can be explained in terms of a band-bending mechanism, complemented by local screening effects. We determine a net charge transfer of 0.09 to 0.13 electrons in favour of the intraplane Cu sites, depending on the interface orientation.