Atomic-level engineering of cuprates and manganites

• Published in: Applied surface science 1997-04, Vol.113, p.189-197
• Main Authors: Bozovic, Ivan, Eckstein, J.N.
• Format: Article
• Language: English
• Subjects: Cuprate superconductors; Manganites; MBE; Nanoengineering
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/S0169-4332(96)00874-4

Using ALL-MBE, we have engineered a novel, artificial (metastable) cuprate superconductor, BiSr 2Ca 7− x Dy x Cu 8O 19+ y , in which only the central Ca layer is doped by Dy. This provides, within a single unit cell, the bottom superconducting electrode, an insulating barrier layer (only few Å thick), and the top superconducting electrode, thus constituting an artificial intra-cell Josephson junction. In this way, we have fabricated the first high- T C tunnel (SIS) junctions. They exhibit significant Josephson supercurrents and very sharp quasiparticle tunneling I- V characteristics. Next, single-crystal thin films of manganites grown by ALL-MBE have shown remarkable anisotropy of colossal magnetoresistance (CMR). We have also fabricated lateral superlattices with alternating stripes (nano-wires) of La 1− x Ca x MnO 3 and La 1− x Sr x MnO 3, few tens of nanometers wide. They show substantial in-plane anisotropy in transport properties, and a fivefold increase in low-field sensitivity. Our most recent results include successful growth of La 1− x Sr x MnO 3 on top of Bi 2Sr 2CaCu 2O 8, and vice versa.