Double specific heat anomaly of the superconducting state of CePt₃Si

CePt₃Si is the first heavy fermion superconductor without a centre of symmetry. Below an antiferromagnetic transition at 2.25 K superconductivity occurs at T_C = 0.73 K. The non-centrosymmetric structure is expected to have significant impact on the nature of the superconducting order parameter. This may be a reason for the unusual shape of the superconducting transition observed in the specific heat. We present specific heat data which clearly show the existence of a double anomaly in the superconducting state, signalling two consecutive phase transitions, as in the uranium based heavy fermion superconductors U_1−xTh_xBe₁₃ and UPt₃.