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Title: Enhancement of the critical temperature in iron-pnictide superconductors by finite size effects
Authors: Araújo, Araújo MAN
García-García, García-García AM
Sacramento, Sacramento PD
Keywords: supercondutividade
sistemas mesoscopicos
Issue Date: 7-Nov-2011
Publisher: Physical Review B
Citation: Physical Review B 84, 172502 (2011)
Abstract: Recent experiments have shown that in agreement with previous theoretical predictions, superconductivity in nanostructures can be enhanced with respect to the bulk (L→∞) limit. Motivated by these results, we study finite size effects (FSEs) in iron pnictide superconductors. We employ a five-band mean-field approach that reproduces quantitatively the band structure of these materials around the Fermi energy. For realistic values of the bulk critical temperature Tcbulk∼20−50 K, we find that Tc(L) has a complicated oscillating pattern as a function of the system size L. For a simplified two-band model we show analytically that these oscillations are caused by fluctuations of the spectral density around the Fermi energy. We identify a scale L∼10 nm for which deviations from mean fields, not included in our model, are small but still Tc(L) is higher than Tcbulk. Similar results are obtained for different boundary conditions and geometries. Finally we show that the differential conductance, an experimental observable, is also very sensitive to FSE.
Type: article
Appears in Collections:FIS - Publicações - Artigos em Revistas Internacionais Com Arbitragem Científica

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