Disorder and quasiparticle interference in heavy-fermion materials

Francesco Parisen Toldin,Jeremy Figgins,Dirk K Morr,Stefan Kirchner

doi:10.1103/physrevb.88.081101

Abstract

Using a large-N approach, we study the effect of disorder in the Kondo-screened phase of heavy-fermion materials. We demonstrate that the strong feedback between the hybridization and the conduction electron charge density magnifies the effect of disorder, such that already small concentrations of defects strongly disorder the materials' local electronic structure, while only weakly affecting their spatially averaged, thermodynamic properties. Finally, we show that the microscopic nature of defects can be identified through their characteristic signatures in the hybridization and quasiparticle interference spectrum.

Highlights

Heavy-fermion materials are characterized by the presence of localized degrees of freedom, i.e., magnetic moments residing on rare-earth or actinide ions and itinerant spd-electronic states and the strong correlations between these degrees of freedom.1 The resulting interplay gives rise to a wide range of ground states ranging from magnetic and superconducting phases2–4 to semiconducting and metallic phases5 with strongly enhanced quasiparticle mass, or without well-defined quasiparticles,6 and even to enigmatic phases with yet unknown order parameters.7 Only recently, scanning tunneling spectroscopy (STS) experiments have succeeded in probing the local electronic structure of several heavy-fermion compounds, such as URu2Si2,8–10 YbRh2Si2,11 CeRhIn5 and CeCoIn5,12,13 at sufficiently low energy and temperature to infer ground-state properties
Using a large-N approach, we study the effect of disorder in the Kondo-screened phase of heavy-fermion materials
We demonstrate that the strong feedback between the hybridization and the conduction electron charge density magnifies the effect of disorder, such that already small concentrations of defects strongly disorder the materials’ local electronic structure, while only weakly affecting their spatially averaged, thermodynamic properties

Summary

Introduction

Heavy-fermion materials are characterized by the presence of localized degrees of freedom, i.e., magnetic moments residing on rare-earth or actinide ions and itinerant spd-electronic states and the strong correlations between these degrees of freedom.1 The resulting interplay gives rise to a wide range of ground states ranging from magnetic and superconducting phases2–4 to semiconducting and metallic phases5 with strongly enhanced quasiparticle mass, or without well-defined quasiparticles,6 and even to enigmatic phases with yet unknown order parameters.7 Only recently, scanning tunneling spectroscopy (STS) experiments have succeeded in probing the local electronic structure of several heavy-fermion compounds, such as URu2Si2,8–10 YbRh2Si2,11 CeRhIn5 and CeCoIn5,12,13 at sufficiently low energy and temperature to infer ground-state properties. We show that a strong feedback between the defect-induced spatial oscillations in the hybridization and the charge density of the conduction band leads to significant disorder in the local electronic properties already for small impurity concentrations.

Results

Conclusion