Dependence of Tc on hydrostatic pressure in a 123 superconductor

Hydrostatic pressure studies on the tetragonal 123 superconductor (La1-xCax)(Ba1.75-xLa0.25+x)Cu3Oy for x=0.1 and variable oxygen content y show that Tc increases rapidly under pressure (+5 K/GPa) for underdoped, optimally doped and overdoped samples. This points to a common cause for the pressure-induced changes in the superconductivity at all levels of doping, with negligible effects from charge transfer. Weak relaxation behavior in Tc is observed only for the most underdoped sample. (orig.)