M. MONNI

One of the most important predictions of the two-gap theory of superconductivity concerns the role of interband scattering (IBS) by impurities. IBS is expected to decrease the critical temperature, Tc, of MgB2 to a saturation value of about 20 K, where the two gaps merge to a single one. These predictions have been partially contradicted by...

In this paper, a 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 σ-band gap, Δσ, evaluated by pointcontact measurements. Up to x=0.2, Bc2 can be well described within a clean limit model and its decrease with x is directly...