$\mathrm{Fe_3GeTe_2}$: A site-differentiated Hund metal

TL;DR

This paper reveals that $ ext{Fe}_3 ext{GeTe}_2$ is a unique Hund metal with site-dependent Hund correlation strength, providing new insights into its magnetic and electronic behaviors relevant for 2D magnetic materials.

Contribution

It introduces the concept of site-differentiated Hund metallicity in $ ext{Fe}_3 ext{GeTe}_2$, a novel understanding of its correlated electronic state.

Findings

$ ext{Fe}_3 ext{GeTe}_2$ is identified as a Hund metal.

The Hund correlation strength varies significantly across different atomic sites.

This site-dependent Hund metallicity explains previously contradictory experimental results.

Abstract

Magnetism in two-dimensional (2D) van der Waals (vdW) materials has lately attracted considerable attention from the point of view of both fundamental science and device applications. Obviously, establishing the detailed and solid understanding of their magnetism is the key first step toward various applications. Although $\mathrm{Fe_3GeTe_2}$ is a representative ferromagnetic (FM) metal in this family, many aspects of its magnetic and electronic behaviors still remain elusive. Here, we report our new finding that $\mathrm{Fe_3GeTe_2}$ is a special type of correlated metal known as 'Hund metal'. Furthermore, we demonstrate that Hund metallicity in this material is quite unique by exhibiting remarkable site-dependence of Hund correlation strength, hereby dubbed 'site-differentiated Hund metal'. Within this new picture, many of previous experiments can be clearly understood including the ones that were seemingly contradictory to one another.