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|Type:||Artigo de periódico|
|Title:||Evolution Of Eu2 + Spin Dynamics In Ba 1-xeu Xfe 2as 2|
|Abstract:||Single crystals of Ba 1-xEu xFe 2As 2 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 0.2, we found a single Eu2 + ESR Dysonian line that presents an isotropic linear increase (Korringa) of its linewidth (ΔH) above T SDW which systematically decreases with decreasing x. In contrast, for a critical concentration x c (0.10<x c<0.20), ΔH 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. © 2012 American Physical Society.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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