Superconductivity in cuprate artificial structures

Superlattices based on standard high temperature superconductors (HTS) such as YBa 2 Cu 3 O 7− x and Bi 2 Sr 2 Cu n Ca n −1 O x have been extensively used to investigate many fundamental issues in HTS physics such as dimensionality, vortex dynamics, proximity effects, epitaxial strain effects, interplay between superconductivity and magnetism. Recently, a different approach based on thin layers of the (Ca, Sr, Ba)CuO 2 compounds ( infinite layers compounds) has been applied to the synthesis of superconducting cuprate heterostructures. Ideal infinite layer (IL) compounds alone are not superconducting; however, in IL-based heterostructures, the occurrence of charge transfer among layers containing different alkaline earth ions can give rise to superconductivity. Structural features of these heterostructures can be engineered in a wide range and, consequently, their superconducting properties are studied. The highlights of these investigations are reviewed here.