Specific Heat Study of Magnetic and Superconducting Transitions in CePt₃Si

Abstract

Measurements of specific heat between 80 mK to 4 K and electrical resistivity between 80 mK to 10 K were carried out for polycrystalline CePt₃Si samples cut into small pieces (typically ∼10 mg). In the specific heat measurements, we observed an antiferromagnetic transition jump at T_N=2.2 K for all the samples, while the heights have large variations. As regards superconductivity, we observed two distinct transition jumps at T_c^l∼0.45 K and T_c^h∼0.75 K, which were the same for all the samples. From the measurements of specific heat and resistivity, systematic relations were found between antiferromagnetic and superconducting transitions. We conclude that antiferromagnetism, whose transition temperature is 2.2 K, coexists with superconductivity, whose transition temperature is T_c^l. In this sample, residual electronic specific heat coefficient in the superconducting state γ_s was quite small, and specific heat divided by temperature below T_c^l decreased almost linearly with decreasing temperature. In order to reveal the characteristic properties of the magnetism and superconductivity of the CePt₃Si system, it is important to study the two superconducting phases with T_c^l and T_c^h, respectively.