Sabina Ruiz-Chavarria

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

The electrical conductivity anisotropy of the σ-bands is calculated for the (Mg,Sc)B2 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 Tc 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 σ-bands is an important parameter for the understanding of the high Tc found in MgB2.