Intraband scattering studies in carbon- and aluminium-doped MgB2

Magnetic field effect on the point-contact spectra of the Al- and C-substituted MgB2 is presented. It is shown that suppression of the pi-band contribution to the spectrum is different in the aluminium- and carbon-doped samples. The carbon substitution leads to a stronger enhancement of the pi-band scattering while the Al-doping does not change the ratio between the pi and sigma scatterings. (c) 2006 Elsevier B.V. All rights reserved.