Thermodynamic study on non-centrosymmetric superconductor UIr by ac calorimetry under high pressure

摘要

We investigated pressure-induced superconductor UIr by the ac heat capacity measurement under high pressure. The heat capacity shows an anomaly at the Curie temperature T_(C1) velence 46 K at ambient pressure and the heat capacity anomaly shifts to the lower temperature side with increasing pressure. The present pressure dependence of T_(C1) was consistent with previous works by the resistivity and magnetization measurements. No heat capacity anomaly was found at T_(C2) and T_(C3) which were clarified by previous ac magnetic susceptibility measurement. This may be due to very small magnetic ordered moments (approx0.05(mu)_(B)/U) of the FM2 and FM3 phases.