Superconductivity on the threshold of magnetism in CePd2Si2 and CeIn3

The magnetic ordering temperature of some rare-earth-based heavy-fermion compounds is strongly pressure dependent and can be completely suppressed at a critical pressure, p(c), making way for novel correlated electron states closer to this quantum critical point. We have studied the clean heavy-fermion antiferromagnets CePd2Si2 and CeIn3 in a series of resistivity measurements at high pressures up to 3.2 GPa acid down to temperatures in the mK region. In both materials, superconductivity appears in a small window of a few tenths of a GPa on either side of p(c). We present detailed measurements of the superconducting and magnetic temperature-pressure phase diagram, which indicate that superconductivity in these materials is enhanced, rather than suppressed, by the closeness to magnetic order.