Optical fingerprints of the electronic band reconstruction in van der Waals magnetic materials

TL;DR

This study investigates how magnetic ordering in van der Waals 2H-$M_x$TaS$_2$ materials affects their charge dynamics and electronic band structure, revealing spectral weight shifts associated with ferromagnetic and antiferromagnetic phases.

Contribution

It provides the first broadband optical analysis linking magnetic order to electronic band reconstruction in vdW magnetic materials.

Findings

Spectral weight shifts from high to low energies in ferromagnetic compositions.

Spectral weight shifts from low to high energies in antiferromagnetic compositions.

Electronic band structure reconstructs along the FM to AFM crossover.

Abstract

We report a broadband study of the charge dynamics in the van der Waals (vdW) magnetic materials 2H-$M_x$TaS$_2$ ($M$ = Mn and Co), which span the onset of both long-range antiferromagnetic (AFM) and ferromagnetic (FM) order, depending on the intercalation $M$ and its concentration $x$. We discover a spectral weight ($SW$) shift from high to low energy scales for FM compositions, while reversely $SW$ is removed from low towards high spectral energies for AFM compounds. This maps the related reconstruction of the electronic band structure along the crossover from the FM to AFM order, which restores an occupation balance in the density of states between spin majority and minority bands of the intercalated 3$d$ elements.