Novel pressure phase diagram of heavy fermion superconductor CePtSi investigated by ac calorimetry

Tateiwa, Naoyuki   ; Haga, Yoshinori   ; Matsuda, Tatsuma; Ikeda, Shugo; Yasuda, Takashi*; Takeuchi, Tetsuya*; Settai, Rikio*; Onuki, Yoshichika

The pressure dependences of the antiferromagnetic and superconducting transition temperatures have been investigated by ac heat capacity measurement under high pressures for the heavy-fermion superconductor CePtSi without inversion symmetry in the tetragonal structure. The Nel temperature = 2.2 K decreases with increasing pressure and becomes zero at the critical pressure 0.6 GPa. On the other hand, the superconducting phase exists in a wider pressure region from ambient pressure to about 1.5 GPa. The pressure phase diagram of CePtSi is thus very unique and has never been reported before for other heavy fermion superconductors.