Orbital magneto-optical response of periodic insulators from first principles

TL;DR

This paper introduces a new first-principles computational method to accurately calculate the orbital magneto-optical response of periodic insulators, enabling better understanding of magnetic effects in materials.

Contribution

It reformulates density matrix perturbation theory for electromagnetic fields in periodic systems, allowing ab initio calculations of magneto-optical responses with efficiency comparable to existing methods.

Findings

Results agree with experimental data for molecules and solids.

Reveals valley Zeeman effect in hexagonal boron nitride.

Enables study of magneto-optical effects in low-dimensional systems.

Abstract

Magneto-optical response, i.e. optical response in the presence of a magnetic field, is commonly used for characterization of materials and in optical communications. However, quantum mechanical description of electric and magnetic fields in crystals is not straightforward as the position operator is ill defined. We present a reformulation of the density matrix perturbation theory for time-dependent electromagnetic fields under periodic boundary conditions, which allows us to treat the orbital magneto-optical response of solids at the \textit{ab initio} level. The efficiency of the computational scheme proposed is comparable to standard linear-response calculations of absorption spectra and the results of tests for molecules and solids agree with the available experimental data. A clear signature of the valley Zeeman effect is revealed in the continuum magneto-optical spectrum of a single layer of hexagonal boron nitride. The present formalism opens the path towards the study of magneto-optical effects in strongly driven low-dimensional systems.