HALL-EFFECT MEASUREMENT ON CU-1234 SUPERCONDUCTORS

The resistivity rho and the Hall coefficient R(H) have been measured f or (Cusimilar to 0.5Tlsimilar to 0.5)Ba2Ca3Cu4Oz and Cusimilar to 0.8S similar to 0.2Ba2Ca3Cu4SOy superconductors. The T-c's of Tl introduced samples increased significantly and reached similar to 125 K (midpoin t) for a sample annealed at 300 degrees C for 10 h in O-2. The T-c of S introduced sample was the same as those of (Cu1-xCx)Ba2Ca3Cu4Oz repo rted previously. The R(H) of CuTl-1234 is significantly larger than th ose of other C or S introduced samples. From these results and univers al relation between T-c and carrier concentration (n) in cuprate oxide superconductors, we can surmise that the n in the CuO2 plane for the CuTl-1234 is in the region of an adequate carrier concentration to the highest T-c in Cu-1234 superconductors. We also found an exact T-2 de pendence of the Hall angle (cot theta = alpha T-2) up to 300 K for the CuTl-1234 and CuS-1234, like for the CuC-1234, though the a values fo r CuTl-1234 are larger. (C) 1997 Academic Press Limited.