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|Type:||Artigo de periódico|
|Title:||Different Gd3+ sites in doped CaB6: An electron spin resonance study|
|Abstract:||The local environment of Gd3+ (4f(7), S=7/2) ions in single crystals of Ca1-xGdxB6 (0.0001less than or similar toxless than or similar to0.01) is studied by means of electron spin resonance (ESR). The spectra for low concentration samples (xless than or similar to0.001) show a split spectrum due to cubic crystal field effects (CFE). The line shape of each fine structure line is Lorentzian, indicating an insulating environment for the Gd3+ ions. For higher concentrations (0.003less than or similar toxless than or similar to0.01), the spectra show a single resonance [g=1.992(4),DeltaH(1/2)approximate to20-60 Oe] with no CFE and Dysonian line shape indicating metallic environment for the Gd3+ ions. For intermediate concentrations, a coexistence of spectra corresponding to insulating and metallic regions is observed. Most of the measured samples show the weak ferromagnetism (WF) as reported for Ca0.995La0.005B6, but, surprisingly, this WF has no effect in our ESR spectra either for metallic or insulating environments. This result suggests that the WF in these systems might be isolated in clusters (defect-rich regions) and its relationship with metallicity is nontrivial.|
|Editor:||American Physical Soc|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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