Electron spin resonance of Gd3+ in the antiferromagnetic heavy fermion CeIn3 and its reference compound LaIn3

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

We report temperature dependent electron spin resonance (ESR) experiments of Gd3+ in CeIn3 and in its reference compound LaIn3 taken in crushed single crystals. For LaIn3 a single Dysonian Gd3+ ESR line with a nearly temperature independent g similar to 2.020(5) is observed, and its linewidth follows a Korringa-like behavior as a function of temperature. From the Korringa rate (Delta H/Delta T similar to 16 Oe/K) and g-shift (Delta g similar to 0.027) we have extracted the exchange parameter between the Gd3+ local moments and the conduction electrons (ce) in this compound. This exchange parameter J(fs) approximate to 20 meV was found to be ce wave-vector independent. For CeIn3, the Gd3+ ESR spectra were found to be weakly temperature dependent and present partly resolved Gd3+ fine-structure. Interestingly, for CeIn3, the g-shift with respect to the g-value of Gd3+ in insulators is negative, in contrast to the positive g-shift found for Gd3+ in LaIn3. These results suggests different electronic structure at the Gd3+ site in the Kondo antiferromagnet host CeIn3. Possibly, Kondo effect may cause a decrease of the s-like conduction electron density of states at the Gd3+ site, giving arise to an exchange interaction only between the Gd3+ local moment and the Ce 4f electrons. (C) 2009 Elsevier B.V. All rights reserved.