Abstract
The structural, magnetic, and superconducting properties of the mixed compounds () () and () were studied. dc resistance, meissner, and shielding measurements have shown that both magnetic Ni and diamagnetic Zn ions destroy the superconductivity in the La-Sr-Cu-O system. Within the Y-Ba-Cu-O system, the replacement of copper by nickel depresses from 93 K () to 50 K (). At higher nickel contents, the phase does not form. The upper critical field of the nickel-doped samples was measured near in dc fields to 23 T. Resistive midpoint transitions yield T/K for the Ni-doped La-Sr-Cu-O () and Y-Ba-Cu-O () systems, respectively. We compare doping results for magnetic and nonmagnetic ions, and discuss the origin of the depression in .
- Received 17 July 1987
DOI:https://doi.org/10.1103/PhysRevB.36.8393
©1987 American Physical Society