Magnetic-ordering, hyperfine, and linear contributions to the low-temperature specific heat of (Y1−xPrx)Ba2Cu3O7−δ

Specific-heat measurements on (${\mathrm{Y}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Pr}}_{\mathit{x}}$)${\mathrm{Ba}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$, for x=0, 0.1, 0.2, 0.3, and 1, with 0.3≤T≤65 K, which include measurements in magnetic fields to 7 T, are reported. The combination of low-temperature and in-field data sllows the separation of hyperfine and magnetic-ordering contributions from the low-temperature linear term ${\gamma }_0$T. The value of ${\gamma }_0$, 200 mJ/mol Pr ${\mathrm{K}}^2$ for x=0.1, 0.2, and 0.3, is substantially lower than that deduced from earlier measurements, but the determination of a cutoff temperature of ∼50 K for this contribution adds to the appearance of heavy-fermion-like behavior.