Extraordinary behaviour of the Y1-xPrxBa2Cu3O7-δ system

Investigations of Y1-xMxBa2Cu3O7-δ (M = Ce, Tn) c-axis oriented thin film specimens show that the rate of depression of Tc with x is larger for M = Th, than for M = Ce and Pr, and suggest that Ce, like Th, is tetravalent in this compound. Hall effect measurements on Y1-xPrxBa2Cu3O7-δ single crystals reveal a T2 dependence of the cotangent of the Hall angle in the normal state and a open-quotes negative Hall anomalyclose quotes below Tc in the superconducting state, in agreement with recent reports. Our research shows that the depth, Δ, of the negative Hall signal scales with T/Tc and that the maximum value of Δ decreases linearly with x and vanishes at x ∼ 0.24. Magnetoresistance measurements on Y1-xPrxBa2Cu3O7-δ single crystals indicate that the irreversibility line H(T*) obeys a universal scaling relation characterized by an m = 3/2 power law near Tc, with a crossover to a more rapid temperature dependence of below T/Tc ∼ 0.6, similar to that observed for polycrystalline specimens. 56 refs., 10 figs