Superconductivity and magnetism in Eu1xPrxBa2Cu3O7δ

G. Nieva, S. Ghamaty, B. W. Lee, M. B. Maple, and Ivan K. Schuller
Phys. Rev. B 44, 6999 – Published 1 October 1991
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Abstract

Measurements of the electrical resistivity ρ as a function of temperature T, and low-temperature specific heat C as a function of T and magnetic field H, have been performed for Pr concentrations 0≤x≤1 in the Eu1xPrxBa2Cu3O7δ system (δ≊0.05). The superconducting critical temperature Tc(x) in the metallic phase (0≤xxc≊0.5) was determined from the resistivity ρ(x,T), while the Néel temperature TN(x) in the insulating phase (xcx≤1) was inferred from specific-heat anomalies due to antiferromagnetic (AFM) ordering of the Pr ions. The effect of ‘‘chemical’’ pressure on Tc(x) in the Y1xPrxBa2Cu3O7δ system is opposite to that of applied hydrostatic pressure. The Pr contributions to the specific heat in the insulating phase have the form C(T)=MT3 for T<TN, characteristic of three-dimensional AFM magnons. In contrast, the Pr contribution to C(T) in the metallic phase takes the form of a broad anomaly that can be described by a spin-1/2 Kondo model. The entropy associated with the Pr specific-heat anomalies in both the metallic and insulating phases is close to R ln2, indicative of a doublet ground state for Pr in the crystalline electric field and a Pr valence close to 4+.

  • Received 17 May 1991

DOI:https://doi.org/10.1103/PhysRevB.44.6999

©1991 American Physical Society

Authors & Affiliations

G. Nieva, S. Ghamaty, B. W. Lee, M. B. Maple, and Ivan K. Schuller

  • Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, California 92093

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Vol. 44, Iss. 13 — 1 October 1991

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