Two Superconducting Transitions in Heavy Fermion CePt3Si

Using small amounts of doping in CePt$_{3}$Si, along with annealing up to 1300 $^{\circ}$C, we have discovered two very distinct superconducting transitions in good analogy to U$_{1-x}$Th$_{x}$Be$_{13}$. We have characterized these samples with specific heat, $\chi $, and $\rho $ in zero and applied magnetic field and created a phase diagram to track the existence of the two transitions as a function of several materials parameters. The sum of the discontinuities, $\Delta $C, in the specific heat at T$_{c1}$ ($\approx $0.8 K) and T$_{c2}$ ($\approx $0.55 K) for both transitions exceeds the size of $\Delta $C for pure CePt$_{3}$Si by over a factor of four. The upper transition appears to be almost totally suppressed with impurites at the 100 ppm level, indicative of non-conventional superconductivity, while the lower transition is much more robust.