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Critical Field of Al-Doped MgB2 Samples: Correlation with the Suppression of Sigma-Band Gap

M. Putti·C. Ferdeghini·M. Monni·I. Pallecchi·C. Tarantini·P. Manfrinetti·A. Palenzona·D. Daghero·R. S. Gonnelli·V. A. Stepanov
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Abstract

In this Letter, the study of the effect of Al substitution on the upper critical field, Bc2, in AlxMg1-xB2 samples is presented. We find a straightforward correlation between Bc2 and the sigma-band gap, Delta_sigma, evaluated by point-contact measurements. Up to x=0.2 Bc2 can be well described within a clean limit model and its decrease with x is directly related to the suppression of Delta_sigma. For larger doping we observed the crossover to the dirty regime driven mostly by the strong decrease of Delta_sigma rather than by the increase of the sigma-band scattering rate

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M. Putti, C. Ferdeghini, M. Monni, I. Pallecchi, C. Tarantini, P. Manfrinetti, A. Palenzona, D. Daghero, R. S. Gonnelli, V. A. Stepanov. 2004-06-16. Critical Field of Al-Doped MgB2 Samples: Correlation with the Suppression of Sigma-Band Gap. https://doi.org/10.1103/physrevb.71.144505

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