PRESSURE-DEPENDENCE OF THE SUPERCONDUCTING TRANSITION-TEMPERATURE OF (Y1-XPRX)BA2CU3O7-DELTA COMPOUNDS - EVIDENCE FOR 4F ELECTRON HYBRIDIZATION

The effect of nearly hydrostatic pressure to 20 kbar on the superconducting transition temperature Tc of (Y1-xPrx)Ba2Cu3O7-δ compounds with 0x0.5 was determined by means of low frequency ac electrical resistivity measurements. The application of pressure to this system reveals striking effects which appear to be associated with the hybridiazation between Pr 4f and valance band states. In this range of pressure P, Tc increases with P for 0&lex&le0.2, exhibits a maximum at approximately 6 kbar for x=0.3, and decreases rapidly with P for x≥x≥0.3. These results suggest there is a pressure-induced electronic phase transition at approximately 6 kbar for x=0.3 that shifts to lower values of P for higher values of x.