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

A sharp change of Tc in polycrystalline NbxTa1–xCy and nanocrystals encapsulated in multiwall carbon nanocages

“…Near x = 1 H c2 (t = 0.7) decreases with decreasing x from a value of pure NbC 0.98 and shows a shallow minimum around x $ 0.9. This feature is in good accord with the reported observations, which suggests the transition from clean to dirty limit [12].…”

“…6b) H c2 (t = 0.7) decreases with decreasing x from a value of pure NbC 0.98 and shows a shallow minimum around x $ 0.9. There are similar observations for R(Ni, Pt) 2 B 2 C compounds (R = Y, Lu) [12]. Fuchs et al [12] have observed that H c2 (t) for YNi 2 B 2 C and LuNi 2 B 2 C decreases with increasing the impurity concentration of Pt, and turns to increase.…”

“…There are similar observations for R(Ni, Pt) 2 B 2 C compounds (R = Y, Lu) [12]. Fuchs et al [12] have observed that H c2 (t) for YNi 2 B 2 C and LuNi 2 B 2 C decreases with increasing the impurity concentration of Pt, and turns to increase. They have explained the observations in terms of the transition from clean to dirty limit.…”

Effect of Pt on the superconducting and magnetic properties of ErNi2B2C

“…Introduction of Pt-atoms at the Ni-sites creates remarkable modifications of the superconducting properties: the superconducting gap becomes isotropic and the material is pushed from the clean to the dirty limit. For example, variation of electronic specific heat C el as a function of temperature in the superconducting state in pure YNi 2 B 2 C follows a power law, C el ∼ (T/T c ) 3 (anisotropic energy gap) whereas it exhibits an exponential T-dependence in the material YNi 1.8 Pt 0.2 B 2 C (isotropic energy gap) [5,6]. T c is not affected significantly with the introduction of Pt (T c ∼ 12.2 K in YNi 1.8 Pt 0.2 B 2 C; T c = 15.5 K in YNi 2 B 2 C); however, variation of the upper critical field H c2 as a function of x clearly shows that the material passes from the clean limit to the dirty limit with the increase of x [7].…”