Upper critical field (H_{c 2}) scaling near a quantum critical point in the heavy-fermion compound CeRhIn₅

We have measured the specific heat of CeRhIn₅ at extreme conditions of low temperatures (T), high pressures (P), and high magnetic fields (H ⊥ c - axis). Discrete forms of the upper critical field H_{c 2} scaling are observed below and above the critical pressure P_{c 1} (= 1.75) GPa. For P < 1.75 GPa, where unconventional superconductivity and magnetism coexist, H_{c 2} linearly increases with decreasing temperature. For P > 2.35 GPa, where only unconventional superconductivity is observed up to the normal state, H_{c 2} shows normal behavior, saturating at low temperatures. In the intermediate pressure, 1.75 GPa < P < 2.35 GPa, where applied magnetic field induces magnetism in the mixed superconducting state, H_{c 2} shows a crossover from normal temperature dependence to the unusual linear T dependence. These observations delineate the interplay between superconductivity and antiferromagnetic fluctuations that exist in the vicinity of the quantum critical point.