dc magnetization measurements on the new Tl-Ca-Ba-Cu-O superconductor show superconductivity with an onset temperature as high as 118 K, 24 K higher than that of a high-quality Eu-${\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$ sample. The resistive onsets of these new superconductors are near 140 K. The magnetic data show complete diamagnetic flux exclusion and 10-15% Meissner expulsion at 10 K.

• Received 29 February 1988

DOI:https://doi.org/10.1103/PhysRevB.37.9742