Pressure and temperature dependence of the critical current density in YBa2Cu3O7-δ thin films

The transport critical current density (Jc) in c-oriented Y-Ba-Cu-O thin films deposited on LaAlO3 was measured under hydrostatic pressure. We find the relative change of Jc under pressure substantially temperature dependent near Tc, and practically temperature independent for T/Tc<0.8. This behavior is discussed in terms of the empirical equation Jc=Jc0(1-T/Tc*)α, with different factors considered to be important in two temperature regions. The change of Jc under pressure for temperatures close to Tc is dominated by the value of α and pressure derivatives of Tc* and α and the pressure derivatives d(lnJc)/dP are sample dependent; for low temperatures the change of Jc is dominated mainly by pressure dependence of Jc0 and is universal for all samples under study.