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Type: Artigo de periódico
Title: Evolution of Eu2+ spin dynamics in Ba1-xEuxFe2As2
Author: Rosa, PFS
Adriano, C
Iwamoto, W
Garitezi, TM
Grant, T
Fisk, Z
Pagliuso, PG
Abstract: Single crystals of Ba1-xEuxFe2As2 were studied by magnetic susceptibility, heat capacity, resistivity, and electron spin resonance (ESR) measurements. Spin-density wave (at T-SDW) and antiferromagnetic (at T-N) phase transitions were mapped as a function of x. For x >= 0.2, we found a single Eu2+ ESR Dysonian line that presents an isotropic linear increase (Korringa) of its linewidth (Delta H) above T-SDW which systematically decreases with decreasing x. In contrast, for a critical concentration x(c) (0.10 < x(c) < 0.20), Delta H decreases with increasing T, suggesting a distinct relaxation process that we associate with a Eu2+ Kondo single impurity regime. The Korringa rate suppression towards the Ba-rich compounds is claimed to be due to the reduction of the q-dependent exchange interaction between the Eu2+ f electrons and the conduction electrons, which is likely associated with an increasing of localization of Fe d electrons. This result may help the understanding of the SDW phase suppression (that can lead to superconductivity) in this class of materials.
Country: EUA
Editor: Amer Physical Soc
Citation: Physical Review B. Amer Physical Soc, v. 86, n. 16, 2012.
Rights: aberto
Identifier DOI: 10.1103/PhysRevB.86.165131
Date Issue: 2012
Appears in Collections:Unicamp - Artigos e Outros Documentos

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