Magneto-optical response of chromium trihalide monolayers: chemical trends

TL;DR

This study computationally investigates the magneto-optical properties of chromium trihalide monolayers, revealing how ligand atom spin-orbit coupling influences their magneto-optical responses, with implications for 2D magnetic materials.

Contribution

It provides a comprehensive theoretical analysis of magneto-optical effects in chromium trihalide monolayers, highlighting chemical trends and the role of ligand atom spin-orbit coupling.

Findings

Magneto-optical response varies with ligand atom (I, Br, Cl).

Spin-orbit coupling of ligand atoms governs magneto-optical strength.

Excitonic effects significantly influence the spectra.

Abstract

Chromium trihalides (CrI$_3$, CrBr$_3$ and CrCl$_3$) form a prominent family of isostructural insulating layered materials in which ferromagnetic order has been observed down to the monolayer. Here we provide a comprehensive computational study of magneto-optical properties that are used as probes for the monolayer ferromagnetic order: magnetic circular dichroism and magneto-optic Kerr effect. Using a combination of density functional and Bethe-Salpeter theories, we calculate both the optical absorption and the magneto-optical Kerr angle spectra, including both excitonic effects and spinorial wave functions. We compare the magneto-optical response of the chromium trihalides series and we find that its strength is governed by the spin-orbit coupling of the ligand atoms (I, Br, Cl).