Thermoelectric Power in a Single-Crystalline CeIrSi3

The thermoelectric power S and the electrical resistivity ρ of a single-crystalline CeIrSi 3 with the non-centrosymmetric tetragonal crystal structure were measured under pressure up to 2.72 GPa in the temperature range from 1.5 to 300 K. The electronic state of CeIrSi 3 is turned from the antiferromagnetic state to superconducting state as a function of pressure. S exhibits a large positive value up to about 52 µV/K, which is characteristic of heavy-fermion systems. S shows a maximum in its temperature dependence due to the Kondo effect and its maximum temperature T S ,max gradually moves to higher temperatures from about 100 K (at ambient pressure) to about 120 K (at 2.72 GPa) by applying the pressure. We also observed the antiferromagnetic transition as the kink in the temperature dependence of S at pressure up to 2.12 GPa.