The loss of anisotropy in MgB2 with Sc substitution and its relation with the critical temperature

Abstract

The electrical conductivity anisotropy of the or-bands is calculated for the (Mg, Sc)B-2 system using a virtual crystal model. Our results reveal that the anisotropy drops with relatively little scandium content (< 30%): this behaviour coincides with the lowering of T-c and the reduction of the Kohn anomaly. This anisotropy loss is also found in the Al and C doped systems. In this work it is argued that the anisotropy, or 2D-character, of the or-bands is an important parameter for the understanding of the high T-c found in MgB2.