Spin-fluctuations and the peak-dip-hump feature in the photoemission spectrum of actinides

TL;DR

This study uses first-principles calculations to link spin fluctuations to the peak-dip-hump features in photoemission spectra of actinides, revealing how these fluctuations influence electronic states and superconductivity.

Contribution

It provides a detailed first-principles analysis of spin fluctuations in actinides and connects these to spectral features and superconducting properties, advancing understanding of their electronic behavior.

Findings

A strong spin-fluctuation peak at 0.5 eV is present in all studied materials.

The peak-dip-hump spectral feature arises from coupling between spin fluctuations and electronic states.

The spin-fluctuation coupling constant correlates with the superconducting transition temperature.

Abstract

We present first-principles multiband spin susceptibility calculations within the random-phase approximation for four isostructural superconducting PuCoIn$_5$, PuCoGa$_5$, PuRhGa$_5$, and nonsuperconducting UCoGa$_5$ actinides. The results show that a strong peak in the spin-fluctuation dressed self-energy is present around 0.5 eV in all materials, which is mostly created by 5$f$ electrons. These fluctuations couple to the single-particle spectrum and give rise to a peak-dip-hump feature, characteristic of the coexistence of itinerant and localized electronic states. Results are in quantitative agreement with photoemission spectra. Finally, we show that the studied actinides can be understood within the rigid-band filling approach, in which the spin-fluctuation coupling constant follows the same materials dependence as the superconducting transition temperature $T_c$.