Low-temperature specific-heat C measurements as a function of temperature T between 0.5 and 30 K are reported for ${\mathrm{Y}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Pr}}_{\mathit{x}}$${\mathrm{Ba}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ compounds with x=0, 0.2, 0.3, 0.4, 0.6, 0.8, and 1.0. The Pr contribution to the specific heat of all of the samples can be described as the sum of a Pr nuclear Schottky anomaly of the form ${\mathit{C}}_{\mathit{N}}$(T)=${\mathit{AT}}^{\mathrm{-}2}$, a linear term ${\mathit{C}}_{\mathit{L}}$(T)=γT, and a Pr magnetic anomaly. For compounds with x≤0.6, which are metallic and superconducting, the Pr magnetic specific-heat anomaly has the same temperature dependence as a Kondo anomaly. For the compounds with x≥0.8, which are insulating, the magnetic specific-heat anomaly is consistent with antiferromagnetic ordering of the Pr ions with Néel temperatures ${\mathit{T}}_{\mathit{N}}$ of 10.9 and 15.7 K for x=0.8 and 1.0, respectively. For T<${\mathit{T}}_{\mathit{N}}$, the antiferromagnetic specific-heat anomaly has the form ${\mathit{C}}_{\mathit{M}}$(T)=${\mathit{MT}}^3$, characteristic of three-dimensional antiferromagnetic magnons.

• Received 8 October 1990

DOI:https://doi.org/10.1103/PhysRevB.43.5430