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Type: Artigo de periódico
Title: Dependence of the magnetocaloric effect on the A-site ionic radius in isoelectronic manganites
Author: Rocco, DL
Coelho, AA
Gama, S
Santos, MD
Abstract: In this work, we explore the magnetocaloric and magnetic properties of isoelectronic manganites R0.6Sr0.4MnO3 (R = La, Pr, Nd, and Sm). Upon substitution of La3+ by smaller rare-earth ions, the average ionic radius < r(A)> of the A-site (A = (R, Sr)) elements systematically decreases. It is found that, with decreasing < r(A)>, the magnetic-ordering temperature decreases from 341K for La0.6Sr0.4MnO3 to 126K for Sm0.6Sr0.4MnO3. Interestingly, the magnetic-entropy change increases with decreasing < r(A)>, reaching Delta S-M = - 8: 4 J/kg K for Delta H = 0 - 20 kOe for Sm0.6Sr0.4MnO3. For manganites, this is a high value of DSM, and it is related to the fact that the compound exhibits first-order magnetic transition. In contrast, the three other compounds exhibit a second order transition. The results indicate that the structural distortions caused by the decreasing < r(A)> couple the spin subsystem to the lattice, thus, inducing a first-order magnetic transition. VC 2013 American Institute of Physics. []
Country: EUA
Editor: Amer Inst Physics
Citation: Journal Of Applied Physics. Amer Inst Physics, v. 113, n. 11, 2013.
Rights: aberto
Identifier DOI: 10.1063/1.4795769
Date Issue: 2013
Appears in Collections:Unicamp - Artigos e Outros Documentos

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