Tracing d-d transitions in FePS$_{3}$ on ultrafast time scales

TL;DR

This paper demonstrates a novel use of time- and angle-resolved photoelectron spectroscopy to directly observe and analyze the ultrafast dynamics of d-d electronic transitions in FePS₃, a 2D magnetic material.

Contribution

It introduces a new experimental method to trace d-d transitions in momentum space and time, revealing their decay mechanisms in a complex quantum material.

Findings

Successfully visualized d-d transition dynamics in FePS₃

Assigned momentum-dependent characteristics to specific d-d transitions

Elucidated decay mechanisms of d-d transitions in a 2D antiferromagnet

Abstract

Excitations between localized 3d states of transition metal ions within crystalline solids, commonly known as d-d transitions, play a pivotal role in diverse phenomena across solid state physics, materials science, and chemistry. These transitions contribute to the coloration in transition metal oxides, catalytic processes on oxide surfaces, and high-temperature superconductivity. They also couple optical excitation to quantized collective phenomena such as phonons and magnons in magnetic systems. Until now, an experimental method to unravel the complex quasiparticle dynamics associated with d-d transitions has remained elusive. We bridge this gap by demonstrating that d-d transitions can be distinctly traced in momentum space and time using time- and angle-resolved photoelectron spectroscopy (trARPES). Through this approach, we can assign specific momentum-dependent characteristics and elucidate the decay mechanisms of specific d-d transitions in FePS$_{3}$, a two-dimensional van der Waals antiferromagnet with a rich array of quantum phenomena stemming from d-d transitions. This study pioneers the use of ARPES in probing the dynamics of d-d transitions across a wide spectrum of solid-state systems.