Scattering makes a difference in circular dichroic angle-resolved photoemission

TL;DR

This paper evaluates the effectiveness of circular-dichroic ARPES in determining orbital characters of electronic structures in quantum materials, considering complex scattering effects.

Contribution

It benchmarks circular-dichroic ARPES as a tool for orbital characterization, analyzing multiple materials and scattering phenomena to improve interpretation accuracy.

Findings

Circular dichroism in ARPES is sensitive to orbital angular momentum.

Multiple scattering effects significantly influence circular dichroic signals.

The study extends analysis to additional materials GdMn$_6$Sn$_6$ and PtTe$_2$.

Abstract

Recent years have witnessed a steady progress towards blending 2D quantum materials into technology, with future applications often rooted in the electronic structure. Since crossings and inversions of electronic bands with different orbital characters determine intrinsic quantum transport properties, knowledge of the orbital character is essential. Here, we benchmark angle-resolved photoelectron emission spectroscopy (ARPES) as a tool to experimentally derive orbital characters. For this purpose we study the valence electronic structure of two technologically relevant quantum materials, graphene and WSe$_2$, and focus on circular dichroism that is believed to provide sensitivity to the orbital angular momentum. We analyze the contributions related to angular atomic photoionization profiles, interatomic interference, and multiple scattering. Regimes in which initial-state properties could be disentangled from the ARPES maps are critically discussed and the potential of using circular-dichroic ARPES as a tool to investigate the spin polarization of initial bands is explored. For the purpose of generalization, results from two additional materials, GdMn$_6$Sn$_6$ and PtTe$_2$ are presented in addition. This research demonstrates rich complexity of the underlying physics of circular-dichroic ARPES, providing new insights that will shape the interpretation of both past and future circular-dichroic ARPES studies.