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Type: Artigo de periódico
Title: Magnetism in Gd-W films
Author: Gadioli, GZ
Rouxinol, FP
Gelamo, RV
dos Santos, AO
Cardoso, LP
de Moraes, MAB
Abstract: Vapor condensation techniques are useful to prepare magnetic alloys whose components have low or even negligible equilibrium mutual solubility. In this work, one of these techniques-sputtering-was used to obtain Gd(x)W(1-x) alloys whose magnetic properties were investigated as a function of the Gd atomic concentration x. Gadolinium and various Gd-based alloys are promising materials for magnetic refrigeration and this was one of the motivations for this study. The Gd(x)-W(1-x) films were sputter deposited from Gd and W targets with x ranging from 0 to 1 as determined by x-ray energy-dispersive spectroscopic analyses. X-ray diffraction patterns indicate that crystalline structures were formed at low and high Gd concentrations, while at intermediate concentrations, the films were amorphous. Magnetization measurements, performed as a function of temperature and with static and alternating applied fields, reveal a spin glasslike behavior in all the W-containing samples for temperatures below the freezing temperature T(f). For low and intermediate Gd concentrations, and for T>T(f), the films were paramagnetic, while a ferromagnetic phase was observed in the Gd-W alloy of the highest Gd content. The magnetocaloric effect was investigated from the magnetization isotherms M versus H, from which the isothermal magnetic entropy variation Delta S(M) as a function of T, for the removal of an applied field of 50 kOe, was determined. It was observed that the maximum value of Delta S(M) for each Delta S(M) versus T curve and the temperature at which these maxima occur, are strongly dependent on x. (C) 2008 American Institute of Physics.
Country: EUA
Editor: Amer Inst Physics
Rights: aberto
Identifier DOI: 10.1063/1.2838462
Date Issue: 2008
Appears in Collections:Unicamp - Artigos e Outros Documentos

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