Crystal Field Effects in CeIrIn5

TL;DR

This paper investigates the crystal field effects in CeIrIn5, revealing broad magnetic responses and challenging existing models, by combining neutron scattering data with theoretical calculations using the Anderson impurity model.

Contribution

It provides the first detailed analysis of crystal field effects in CeIrIn5, incorporating broad spectral features and advanced modeling with the Anderson impurity model.

Findings

Broad magnetic response observed at 10 K in neutron spectra

Crystal field levels are broad, with ~10 meV width

Theoretical calculations align with experimental data using NCA

Abstract

In this work, we study crystalline electric field effects in the heavy fermion superconductor CeIrIn5. We observe two regions of broad magnetic response in the inelastic neutron scattering spectra at 10 K. The first corresponds to the transition between the gamma7 groundstate doublet and the first excited state doublet at 4 meV interwoven with a broad quasielastic contribution. The second region corresponds to the transition between the ground state and the second excited state doublet at 28 meV. The large Lorentzian half-widths of the peaks (~10 meV) calls into question calculations for the specific heat and magnetic susceptibility that assume sharp crystal field levels. Consequently, we have calculated the inelastic neutron scattering spectra and magnetic susceptibility using the Anderson impurity model within the non-crossing approximation (NCA) including the effects of crystal field level splitting.