Superconductivity in epitaxial Bi2Sr2CuO6/Bi2Sr2CaCu2O8 superlattices: The superconducting behavior of ultrathin cuprate slabs

Utilizing atomic layer-by-layer molecular beam epitaxy (ALL-MBE), the authors have synthesized a series of high-quality superlattices in which ultrathin slabs (one-half unit cell thick) of the high-Tc superconductor Bi2Sr2CaCu2O8 alternate with up to five such layers of the low-Tc Bi2Sr2Cu1O6phase. In all these superlattices they found Tc to be essentially equal to that of the high-Tc Bi2Sr2CaCu2O8 phase itself, which indicates that this cuprate is a 2D superconductor insofar as the interslab coupling plays at best a secondary role. Furthermore, it is demonstrated that Tc need not be reduced at heterostructure interfaces