Pressure-induced superconductivity and large upper critical field in the noncentrosymmetric antiferromagnet CeIrGe₃

We report on the discovery of superconductivity in the noncentrosymmetric antiferromagnet CeIrGe₃ below 1.5 K at a pressure of 20 GPa. We performed electrical resistivity measurements in single crystals of CeIrGe ₃ in the temperature range 0.04-300 K at pressures up to 24 GPa. From these measurements we deduced the P-T phase diagram. The data imply a crossover from localized to itinerant 4f electrons of the type caused by a Kondo-lattice phenomenon as pressure increases. The antiferromagnetic phase weakens with pressure and eventually vanishes above 22 GPa, indicative of the occurrence of a quantum critical point. Superconductivity appears inside the antiferromagnetic phase near this critical point. After the disappearance of the magnetic ordering a non-Fermi-liquid behavior is observed. Resistivity measurements taken at 24 GPa in magnetic fields up to 8 T strongly suggest that CeIrGe₃ has a very large upper critical field for H ∥ [001].