We report the discovery of pressure-induced superconductivity in ferromagnetic UIr, which lacks inversion symmetry in the crystal structure. The Curie temperature T C1 = 46 K at ambient pressure decreases with increasing pressure, reaching a value of 11 K at 1.5 GPa. It presumably decreases further up to about P c1 = 1.7 GPa. The ferromagnetic region named 'F1' exists up to P c1 . A second magnetic phase named 'F2' with a low ferromagnetic moment appears in the pressure range from 1.9 to 2.4 GPa. In the 'F2' phase, the magnetic transition temperature T C2 decreases with pressure, from 18 K at 1.9 GPa to approximately zero at P C2 = 2.6-2.7 GPa. In this critical pressure region, superconductivity appears below T sc = 0.14 K.

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The antiferromagnet CeNiGe 3 exhibits superconductivity under pressure. The Néel temperature initially increases with increasing pressure up to 3 GPa and then becomes zero at a critical pressure (P C ) that is located at approximately 7 GPa. We found that superconductivity emerges from 1.7 GPa in the antiferromagnetic (AF) phase removed from P C . The superconductivity is realized in a wide pressure region including P C . The coefficient A in the resistivity and the upper critical field (H c2 ) significantly change against pressure. A feature of CeNiGe 3 is that the moderate heavy fermion state in the AF phase induces superconductivity.

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Pressure-induced superconductivity is found in UIr without inversion symmetry. The pressuretemperature phase diagram has been investigated by means of the electrical resistivity, ac-susceptibility and magnetization measurements under high pressure. The phase diagram consists of three magnetic phases FM1-3 and a superconducting phase. The huge enhancement of residual resistivity and the negative magnetoresistance are found in the intermediate pressure region. These behavior may be induced by the pressure-induced structural phase transition and the accompanied phase separation in this pressure range. The superconducting phase with narrow pressure range is embedded in the FM3 phase, adjacent to zero-temperature FM3-to-nonmagnetic transition. The temperature dependence of resistivity above T SC follows non-Fermi liquid form of T 1:6 . From these experimental facts, superconductivity is considered to be associated with the ferromagnetic fluctuation.