Probing the electronic structure of pure and doped CeMIn(5) (M=Co,Rh,Ir) crystals with nuclear quadrupolar resonance

We report calculations of the electric-field gradients (EFGs) in pure and doped CeMIn(5) (M=Co, Rh, and Ir) compounds and compare with experiment. The degree to which the Ce 4f electron is localized is treated within various models: the local-density approximation, generalized gradient approximation (GGA), GGA+U, and 4f-core approaches. We find that there is a correlation between the observed EFG and whether the 4f electron participates in the band formation or not. We also find that the EFG evolves linearly with Sn doping in CeRhIn(5), suggesting the electronic structure is modified by doping. In contrast, the observed EFG in CeCoIn(5) doped with Cd changes little with doping. These results indicate that nuclear quadrupolar resonance is a sensitive probe of electronic structure.772

Coexistence of antiferromagnetism and superconductivity in CeCo(In0.9Cd0.1)5: A spin lattice relaxation study

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

Interacting antiferromagnetic droplets in quantum critical CeCoIn5.

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

Disorder in quantum critical superconductors

In four classes of materials - the layered copper oxides, organics, iron pnictides and heavy-fermion compounds - an unconventional superconducting state emerges as a magnetic transition is tuned towards absolute zero temperature, that is, towards a magnetic quantum critical point (QCP). In most materials, the QCP is accessed by chemical substitution or applied pressure. CeCoIn 5 is one of the few materials that are 'born' as a quantum critical superconductor and, therefore, offers the opportunity to explore the consequences of chemical disorder. Cadmium-doped crystals of CeCoIn 5 are a particularly interesting case where Cd substitution induces long-range magnetic order, as in Zn-doped copper oxides. Applied pressure globally suppresses the Cd-induced magnetic order and restores bulk superconductivity. Here we show, however, that local magnetic correlations, whose spatial extent decreases with applied pressure, persist at the extrapolated QCP. The residual droplets of impurity-induced magnetic moments prevent the reappearance of conventional signatures of quantum criticality, but induce a heterogeneous electronic state. These discoveries show that spin droplets can be a source of electronic heterogeneity and emphasize the need for caution when interpreting the effects of tuning a correlated system by chemical substitution. © 2014 Macmillan Publishers Limited

Probing the electronic structure of pure and doped CeM In5 (M=Co,Rh,Ir) crystals with nuclear quadrupolar resonance

We report calculations of the electric-field gradients (EFGs) in pure and doped CeM In5 (M=Co, Rh, and Ir) compounds and compare with experiment. The degree to which the Ce4f electron is localized is treated within various models: the local-density approximation, generalized gradient approximation (GGA), GGA+U, and 4f -core approaches. We find that there is a correlation between the observed EFG and whether the 4f electron participates in the band formation or not. We also find that the EFG evolves linearly with Sn doping in CeRhIn5, suggesting the electronic structure is modified by doping. In contrast, the observed EFG in CeCoIn5 doped with Cd changes little with doping. These results indicate that nuclear quadrupolar resonance is a sensitive probe of electronic structure. © 2008 The American Physical Society

Probing the electronic structure of pure and doped CeM In5 (M=Co,Rh,Ir) crystals with nuclear quadrupolar resonance

We report calculations of the electric-field gradients (EFGs) in pure and doped CeM In5 (M=Co, Rh, and Ir) compounds and compare with experiment. The degree to which the Ce4f electron is localized is treated within various models: the local-density approximation, generalized gradient approximation (GGA), GGA+U, and 4f -core approaches. We find that there is a correlation between the observed EFG and whether the 4f electron participates in the band formation or not. We also find that the EFG evolves linearly with Sn doping in CeRhIn5, suggesting the electronic structure is modified by doping. In contrast, the observed EFG in CeCoIn5 doped with Cd changes little with doping. These results indicate that nuclear quadrupolar resonance is a sensitive probe of electronic structure. © 2008 The American Physical Society