Specific heat of URu₂Si₂: Effect of pressure and magnetic field on the magnetic and superconducting transitions

Specific heats were measured in the range 0.3 ≤T≤30 K for 0≤H≤7T and P=0, and for H=0 and 0≤P≤6.3 kbar. For H=0 and P=0, the measurements were extended to 0.15K. Above the superconducting transition the H=0 and 7T data can be superimposed. For the magnetic transition near T0 = 18K, T0 increased with increasing P accompanied by a broadening and attenuation of the specific heat anomally. The superconducting transition near Tc = 1.5 K was broadened, attenuated and shifted to lower temperatures for both increasing P and H. The superconducting transition is similar to that of UPt3, and both the temperature dependence of the superconducting state specific heat and the derived parameters are consistent with an unconventional polar-type pairing. © 1990.