SUPERCONDUCTIVITY IN EPITAXIAL BI2SR2CUO6/BI2SR2CACU2O8 SUPERLATTICES - THE SUPERCONDUCTING BEHAVIOR OF ULTRATHIN CUPRATE SLABS

Utilizing atomic layer-by-layer molecular beam epitaxy (ALL-MBE), we have synthesized a series of high-quality superlattices in which ultrathin slabs (one-half unit cell thick) of the high-T(c) superconductor Bi2Sr2CaCu2O8 alternate with up to five such layers of the low-T(c) Bi2Sr2Cu1O6 phase. In all these superlattices we found T(c) to be essentially equal to that of the high-T(c) 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 T(c) need not be reduced at heterostructure interfaces.