In this paper we present a combined analysis of the electron transport properties of polycrystalline
MgB2
samples, both in the normal and in the superconducting state. This study is aimed at
checking the applicability of multiband models to the evaluation of band conduction
parameters as well as at addressing the role of some disorder typologies (Mg
inclusions, low-level SiC doping) in affecting them. Normal-state resistivities, suitably
rescaled to take into account the grain connectivity, were first analysed in the
framework of the model formulated by Mazin et al (2002 Phys. Rev. Lett. 89
107002), where we introduced transport spectral functions calculated from the
standard Eliashberg functions. The band scattering rates were obtained: the impurity
σ
band scattering rate was found to be weakly dependent on magnetic field in all
the analysed samples and to increase with SiC doping. Accordingly, intraband
diffusivities obtained by analysing the upper critical field in the framework
of Gurevich’s model (2003 Phys. Rev. B 67 184515) show a decrease of the
σ
band diffusivity in the SiC-doped sample, whereas no remarkable doping effect was found in the
π
band.