We present an In(1) NQR study on the heavy-fermion (HF) compound CeCo(In1-xCdx)5(x = 0.10) . Bulk measurements indicate that Cd doping acts as an electronic tuning agent in CeCoIn5, and that superconductivity (SC) and antiferromagnetism (AFM) may coexist at ambient pressure for 0.05 < x < 0.15. For x = 0.10, the nuclear spin lattice relaxation rate shows a broad peak at the Néel temperature TN = 2.8 K, with a subsequent onset of SC at Tc ≃ 1.2 K. Our results provide strong evidence for microscopic coexistence of these two ground states. The nuclear magnetization recovery curves in both the ordered and mixed states reveal a single T1-component, which suggests a homogeneous nature of the Ce-4f1 electronic state. © 2007 Elsevier B.V. All rights reserved.

The heavy fermion superconductor CeCoIn5 can be tuned between superconducting and antiferromagnetic ground states by hole doping with Cd. Nuclear magnetic resonance data indicate that these two orders coexist microscopically with an ordered moment approximately 0.7 microB. As the ground state evolves, there is no change in the low-frequency spin dynamics in the disordered state. These results suggest that the magnetism emerges locally in the vicinity of the Cd dopants.