Direct measurement of the localized-itinerant transition, hybridization and antiferromagnetic transition of 5f electrons

TL;DR

This study uses angle-resolved photoelectron spectroscopy to directly observe the evolution of 5f electron behavior, hybridization, and magnetic transitions in USb2, revealing the complex interplay of localized and itinerant states.

Contribution

It provides the first direct experimental evidence of the band structure evolution across localized-itinerant and magnetic transitions in 5f electrons of uranium-based heavy-fermion compounds.

Findings

Observation of two heavy quasi-particle bands of 5f electrons.

Detection of energy gaps opening at the AFM transition (~203 K).

Identification of hybridization between localized 5f electrons and conduction bands at ~120 K.

Abstract

In heavy-fermion compounds, f electrons show both itinerant and localized behaviour depending on the external conditions, and the hybridization between localized f electrons and itinerant conduction bands gives rise to their exotic properties like heavy-fermions, magnetic orders and unconventional superconductivity. Duo to the risk of handling radioactive actinide materials, the direct experimental evidence of the band structure evolution across the localized-itinerant and magnetic transitions for 5f electrons is lacking. Here, by using angle-resolved photoelectron spectroscopy, we revealed the dual nature (localized vs itinerant) and the development of two different kinds of heavy quasi-particle bands of 5f electrons in antiferromagnetic (AFM) USb2. Partially opened energy gaps were observed on one quasi-particle 5f band cross the AFM transition around 203 K, indicating that the magnetic orders in USb2 are of spin density wave (SDW) type similar to Cr. The localized 5f electrons and itinerant conduction bands hybridize to form another heavy quasi-particle band at about 120 K, and then open hybridization gaps at even lower temperature. Our results provide direct spectral demonstration of the localized-itinerant transition, hybridization and SDW transition of 5f electrons for uranium-based materials.