Interfacial defects in YBa₂Cu₃O₇{plus 45 degree rule}PrBa₂Cu₃O₇-heterostructures on SrTiO₃ substrates

The interfaces of YBa₂Cu₃O₇{plus 45 degree rule}PrBa₂Cu₃O₇-heterostructures grown epitaxially on [001]-SrTiO₃ substrates were investigated by means of high-resolution electron microscopy and electron diffraction. Misfit dislocation arrays could be observed in the YBa₂Cu₃O₇{plus 45 degree rule}PrBa₂Cu₃O₇ interfaces and inside the first YBa₂Cu₃O₇ layer close to the YBa₂Cu₃O₇/SrTiO₇₃ interface. In the PrBa₂Cu₃O₇ layers a structural modulation was found near the interface. This is explained by the ordering of oxygen vacancies due to compressive strain induced by the adjoining YBa₂Cu₃O₇ layers.