Itinerant Nature of U 5f States in Uranium Mononitride UN Revealed by Angle Resolved Photoelectron Spectroscopy

TL;DR

This study uses angle resolved photoelectron spectroscopy to reveal that U 5f electrons in uranium nitride are itinerant, forming dispersive bands and Fermi surfaces, with minimal spectral changes across the antiferromagnetic transition.

Contribution

It provides direct experimental evidence that U 5f electrons in UN are itinerant, supporting band-structure calculations and clarifying the electronic origin of its magnetic properties.

Findings

U 5f states form dispersive bands and Fermi surfaces

Spectral features show minimal change across magnetic transition

Fermi surface shapes are highly three-dimensional

Abstract

The electronic structure of the antiferromagnet uranium nitride (UN) has been studied by angle resolved photoelectron spectroscopy using soft X-rays (hn=420-520 eV). Strongly dispersive bands with large contributions from the U 5f states were observed in ARPES spectra, and form Fermi surfaces. The band structure as well as the Fermi surfaces in the paramagnetic phase are well explained by the band-structure calculation treating all the U 5f electrons as being itinerant, suggesting that itinerant description of the U 5f states is appropriate for this compound. On the other hand, changes in the spectral function due to the antiferromagnetic transition were very small. The shapes of the Fermi surfaces in a paramagnetic phase are highly three-dimensional, and the nesting of Fermi surfaces is unlikely as the origin of the magnetic ordering.