Specific Heat and de Haas–van Alphen Experiments on the Heavy-Fermion Superconductor CePt3Si

Specific heat and de Haas–van Alphen (dHvA) measurements were performed on a high-quality single crystal of CePt 3 Si without inversion symmetry in the tetragonal crystal structure. We observed distinct peaks in the specific heat C at the superconducting transition temperature T c =0.46 K and the antiferromagnetic ordering temperature T N =2.25 K, compared to the previous data, indicating an improvement of the sample quality. The temperature dependence of the electronic specific heat coefficient C e / T below about 0.3 K is well described by the equation of C e / T =γ s +β s T with γ s =34.1 mJ/(K 2 ·mol) and β s =1290 mJ/(K 3 ·mol), evidencing the existence of line nodes in the superconducting energy gap. Furthermore, the electronic specific heat coefficient γ s in the superconducting state indicates a nonlinear magnetic field dependence \(γₛ(H)∝√H\), which also supports the presence of line nodes. We did not observe a discontinuous change of the Fermi surface at P AF =0.6 GPa where the Néel temperature becomes zero, but observed a new dHvA branch above 1.5 GPa of which the cyclotron effective mass decreased steeply as a function of pressure from 19 m 0 at 2.0 GPa to 11 m 0 at 2.7 GPa.