A new heavy-fermion superconductor CeIrIn5: A relative of the cuprates?

CeIrIn5 is a member of a new family of heavy-fermion compounds and has a So mmerfeld specific-heat coefficient of 720 mJ/molK(2). It exhibits a bulk, t hermodynamic transition to a superconducting state at T-c = 0.40 K: below w hich the specific heat decreases as T-2 to a small residual T-linear value. Surprisingly, the electrical resistivity drops below instrumental resoluti on at a much higher temperature T-0 = 1.2 K. These behaviors are highly rep roducible and field-dependent studies indicate that T-0 and T-c arise from the same underlying electronic structure. The layered crystal structure of CeIrIn5 suggests a possible analogy to the cuprates in which spin/charge pa ir correlations develop a ell above T-c.