Superconductivity on the threshold of magnetism in CePd₂Si₂and CeIn₃

Abstract

The magnetic ordering temperature of some rare earth based heavy fermion\ncompounds is strongly pressure-dependent and can be completely suppressed at a\ncritical pressure, p$_c$, making way for novel correlated electron states close\nto this quantum critical point. We have studied the clean heavy fermion\nantiferromagnets CePd$_2$Si$_2$ and CeIn$_3$ in a series of resistivity\nmeasurements at high pressures up to 3.2 GPa and down to temperatures in the mK\nregion. In both materials, superconductivity appears in a small window of a few\ntenths of a GPa on either side of p$_c$. We present detailed measurements of\nthe superconducting and magnetic temperature-pressure phase diagram, which\nindicate that superconductivity in these materials is enhanced, rather than\nsuppressed, by the closeness to magnetic order.\n