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

Abstract

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 = 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 (∼0.05μ_B/U) of the FM2 and FM3 phases.

Keywords:

• ac calorimetry
• Superconductivity
• Pressure phase diagram
• UIr

Acknowledgements

This work was financially supported by the Grant-in-Aid for Creative Scientific Research (15GS0213), Scientific Research of Priority Area and Scientific Research (A) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT).