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Type: Artigo de periódico
Title: Effect of volume variation on the properties of the Kondo system (La1-xCex)(3)Al
Author: Medina, AN
Hayashi, MA
Cardoso, LP
Gama, S
Gandra, FG
Abstract: We have measured the electrical resistivity and ac magnetic susceptibility (chi)(T) of (La1-xCex)(3)Al, for 0 less than or equal to x less than or equal to 1, and the electrical resistivity of (Ce1-zYz)(3)Al, for 0 less than or equal to z less than or equal to 0.1. The system was characterized using x-ray diffraction and metallography. From x-ray data we were able to determine the structure for all samples to be hexagonal and that the unit-cell volume decreases linearly in going from the La-rich side to the Ce-rich side. The results show that La3Al is a superconductor below 6.2 K a:nd that T-c decreases rapidly with the increase of the Ce concentration. For x > 0.04 we observed a minimum in the resistivity and a reduction of the effective magnetic moment of Ce due to a strong compensation promoted by the Kondo effect. Our results show that the Kondo temperature increases with Ce and Y concentration, according to the reduction of the unit-cell volume. We also show that the antiferromagnetic transition temperature goes through a maximum at z = 0.025, indicating that there is an interplay between superconductivity, antiferromagnetic ordering, and the Kondo effect. A diagram illustrating the evolution of the T-K and T-N is :presented. The electronic specific heat (gamma) increases with the Ce concentration showing a maximum around x approximate to 0.4. It was also possible to determine values for the rho J product and the relative variation of the exchange parameter.
Country: EUA
Editor: American Physical Soc
Citation: Physical Review B. American Physical Soc, v. 57, n. 10, n. 5900, n. 5905, 1998.
Rights: aberto
Identifier DOI: 10.1103/PhysRevB.57.5900
Date Issue: 1998
Appears in Collections:Unicamp - Artigos e Outros Documentos

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