Pressure dependence of superconducting transition temperature and of hall constant in high- Tc Cu-oxide superconductors

Abstract

The pressure derivative of T c in the hole-doped superconductors having relatively lower carrier concentration is shown to change the sign from positive to negative at a certain pressure with a maximum of T c , while it is negative in the highly-doped ones, which is confirmed as a general feature in these compounds. The Hall constants of the samples YBa 2Cu 3O 7, CaBaLaCu 3O 7−y, YBa 2Cu 4O 8, Bi 2Sr 2CaCu 2O 8 and Tl 2Ba 2CuO 6+y is found to increase by about 10%/GPa which is almost the same amount that estimated by Yamada et al. from the Madelung energy calculation for YBa 2Cu 4O 8.