Band Excitations in CePd$_3$: A Comparison of Neutron Scattering and ab initio Theory

TL;DR

This study combines neutron scattering experiments and ab initio calculations to analyze the magnetic excitations in CePd$_3$, revealing that the Q-dependence arises from particle-hole excitations within hybridized bands, demonstrating increasing coherence at lower temperatures.

Contribution

It provides a quantitative comparison between neutron scattering data and ab initio theory for CePd$_3$, confirming the role of f-d hybridized band excitations in magnetic properties.

Findings

Q-dependence caused by particle-hole excitations in hybridized bands

Excellent agreement between experiment and ab initio calculations

Coherence of f-d hybridized bands increases with decreasing temperature

Abstract

Intermediate valence compounds containing rare earth or actinide ions are archetypal systems for the investigation of strong electron correlations. Their effective electron masses of 10 to 50 times the free electron mass result from a hybridization of the highly localized $f$-electrons with the more itinerant $d$-electrons, which is strong enough that their properties are dominated by on-site electron correlations. To a remarkable degree, this can be modeled by the Anderson Impurity Model, even though the $f$-electrons are situated on a periodic lattice. However, in recent years, there has been increasing evidence that the dynamic magnetic susceptibility of intermediate valence compounds is not purely local, but shows variations across the Brillouin zone that have been ascribed to $f$-band coherence. So far, this has been based on simplified qualitative models. In this article, we present a quantitative comparison of inelastic neutron scattering from a single crystal of CePd$_3$, measured in four-dimensional (Q,$\omega$)-space, with ab initio calculations, which are in excellent agreement on an absolute scale. Our results establish that the Q-dependence of the scattering is caused by particle-hole excitations within $f$-$d$ hybridized bands that grow in coherence with decreasing temperature.