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

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

arXiv comment5 pages, 4 figures

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• Thermal conductivity of Al-doped MgB2: Impurity scattering and the validity of the Wiedemann-Franz law
• Local Tunneling Study of Three-Dimensional Order Parameter in the $\pi$-band of Al-doped MgB${}_2$ Single Crystals
• de Haas-van Alphen effect investigations of the electronic structure of pure and aluminum-doped MgB_2
• Theory of vortices in hybridized ballistic/diffusive-band superconductors
• Ballistic and diffusive: theory of vortices in the two-band superconductor MgB2
• Anomalous thermoelectric power of Mg1-xAlxB2 system with x = 0.0 to 1.0
• Band filling and disorder effects on the normal state thermoelectric behavior in MgB2
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