Thermodynamics Investigation on Pressure-induced Superconductor CeNiGe3 by ac Calorimetry

We measured the heat capacity of the pressure-induced superconductor CeNiGe3 by the ac calorimetry under high pressure up to 2.4 GPa using a single crystal sample grown by the Bi-flux method. The heat capacity C-ac shows the lambda-type anomaly at Neel temperature T-N. The pressure dependence of T-N is consistent with those determined previous studies by the resistivity measurement under high pressure. At 2.1 and 2.4 GPa, the heat capacity anomaly was observed around 0.3 K. This temperature is close to the superconducting transition temperature T-sc determined by the previous resistivity measurement. Therefore, the heat capacity anomaly may be due to the superconducting transition. The value of T-sc by the present heat capacity measurement was larger than those by the resistivity measurement. This might reflect a sample dependence.