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Abstract |
Low-temperature specific-heat C measurements as a function of temperature T between 0.5 and 30 K are reported for Y1-xPrxBa2Cu3O7-δ 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 CN(T)=AT-2, a linear term CL(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 TN of 10.9 and 15.7 K for x=0.8 and 1.0, respectively. For T<TN, the antiferromagnetic specific-heat anomaly has the form CM(T)=MT3, characteristic of three-dimensional antiferromagnetic magnons. |
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