Point-contact measurements on the carbon and aluminium substituted MgB2 samples are performed to study a development of the two gap superconductivity . In the carbon substituted MgB2 the large gap on the σ-band is decreased in an essentially linear fashion with increasing the carbon concentrations. The changes in the small gap Δ π up to 3.8 % C are proportionally smaller but for the heavily doped sample with 10 % C and Tc = 22 K both gaps are still present, and significantly reduced, consistent with a strong essentially linear, reduction of each gap with the transition temperature [2,3]. A comparison with the aluminium doped material is made as well.
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 P. Samuely et al., Phys. Rev. B 68, 020505(R) (2003).
 Z. Holanova et al., Phys. Rev. B accepted
* The work has been done in collaboration with P. Szabo, Z. Holanova, R.H.T. Wilke, S. Bud'ko and P.C. Canfield