Thermodynamics study on the heavy fermion superconductor under high pressure

Tateiwa, Naoyuki   ; Haga, Yoshinori   ; Matsuda, Tatsuma; Ikeda, Shugo; Nakashima, Miho*; Thamizhavel, A.*; Takeuchi, Tetsuya*; Settai, Rikio*; Onuki, Yoshichika

I will show our recent investigations on the heavy femion superconductors by the ac calorimetry method under pressure. The method is powerful tool since the high sensitive measurement of the heat capacity is possible. I will present our study on superconductivity in CePtSi with the non-centrosymmetric tetragonal structure. Superconductivity with the transition temperature =0.75K is realized in the long-range antiferromagnetic ordered state with the Nel temperature =2.2K. We determine the pressure phase diagram of CePtSi. The Nel temperature decreases with increasing pressure and becomes zero at the critical pressure 0.6GPa. On the other hand, the superconducting phase exists in a wider pressure region from ambient pressure to about 1.5 GPa. There is no anomalous singular behavior in the pressure dependences of the electronic specific heat coefficient around . This suggests that the superconductivity in CePtSi differs from those observed around the quantum critical point such as in CeIn.