LaNiO3 buffer layers for high critical current density YBa2Cu3O7-delta andTl2Ba2CaCu2O8-delta films

We demonstrate high critical current density superconducting films of YBa2C u3O7-delta (YBCO) and Tl2Ba2CaCu2O8-delta (Tl-2212) using LaNiO3 (LNO) buff er layers. YBCO films grown on an LNO buffer layer have only a slightly low er J(c) (5 K, H = 0) than films grown directly on a bare LaAlO3 substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorde r and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reduct ions in J(c) at all temperatures and fields compared to those grown on bare LaAlO3, correlating to both a-axis grain and nonsuperconducting phase form ation. LNO could be a promising buffer layer for both YBCO and Tl-based sup erconducting films in coated conductor applications. (C) 1999 American Inst itute of Physics. [S0003-6951(99)02242-1].