Non-magnetic superconducting R(Ni,Pt)2B2C compounds (R=Y, Lu) in the clean and dirty limit

Substitutional disorder in Y(Ni1-xPtx)2B2C and Lu(Ni1-xPtx)2B2C is found to reduce relevant quantities as Tc, the upper critical field Hc2(0) at T=0 and a characterisitic positive curvature of Hc2(T) near Tc observed for these compounds. Starting from the clean limit at x=0, a dirty-limit-like state is achieved near x=0.2 in qualitative accordance with a two-band model. The electronic specific heat ces(T) follows, for the clean limit superconductors YNi2B2C and LuNi2B2C, a power law whereas an exponential BCS-like temperature dependence is observed in the dirty limit. Nevertheless, the electronic specific heat parameter gamma(H) in the mixed state shows significant deviations from the linear gamma(H) law also in the dirty limit.