Artigos de divulgação na mídia da Embrapa Pantanal: autores e temáticas do domínio.

Trata-se de uma pesquisa descritiva que apresenta parte dos resultados de uma pesquisa de mestrado. Foi feito o recorte, para as análises métricas, das publicações ADM Artigos de Divulgação na Mídia, produzidas e editadas pela Embrapa Pantanal, no período 2007 a 2012. Pretende-se responder a algumas perguntas fundamentais: a) Quais autores colaboraram na construção desse universo e como se caracterizam? b) Como é o universo conceitual formado pelo mapeamento das temáticas tratadas nos artigos publicados

Flux-dynamics associated with the Second Magnetisation Peak in iron-pnictide Ba_{1-x}K_xFe_2As_2

We report on isofield magnetic relaxation data on a single crystal of $Ba_{1-x}K_xFe_2As_2$ with superconducting transition temperature $T_c$= 32.7 K which exhibit the so called fish-tail effect. A surface map of the superconducting transition temperature shows that the superconducting properties are close to homogeneous across the sample. Magnetic relaxation data, M(t), was used to obtain the activation energy U(M) in order to study different vortex dynamics regimes. Results of this analysis along with time dependent measurements as a function of field and temperature extended to the reversible region of some M(H) curves demonstrate that the irreversibility as well the second magnetization peak position, $H_p(T)$, are time dependent and controlled by plastic motion of the vortex state. In the region delimited by a characteristic field Hon (well below $H_p$), and $H_p$, the vortex dynamics is controlled by collective pinning. For fields below Hon the activation energy, $U_0$, increases with field as expected for collective pinning, but the pinning mechanism is likely to be in the single vortex limit.Comment: 8 pages, 8 figures, one tabl