CeRhIn5 is a new heavy-electron material that crystallizes in a quasi-2D structure that can be viewed as alternating layers of CeIn3 and RhIn2 stacked sequentially along the tetragonal c axis. Application of hydrostatic pressure induces a first-order-like transition from an unconventional antiferromagnetic state to a superconducting state with T(c) = 2.1 K.

We report a new family of Ce-based heavy-fermion compounds whose electronic specific heat coefficients range from about 400 to over 700mJ/mol-Ce K2. Crystals in this family form as CenTmIn3n-2m, where T = Rh or Ir, n = 1 or 2, and m = 1, with a tetragonal structure that can be viewed as m-layers of CeIn3 units stacked sequentially along the c-axis with intervening m-layers of TIn2. Ambient and high-pressure studies show that the quasi-2D layers of CeIn3 produce unconventional superconducting and magnetic ground states. This family should enable new understanding of the relationship between magnetism and superconductivity in heavy-fermion materials and more generally of why heavyfermion superconductivity prefers to develop in one structure type and not another. © 2001 Elsevier Science B.V. All rights reserved.