Effective model for studying optical properties of lead-halide perovskites

TL;DR

This paper develops an effective symmetry-based model to study the optical properties of lead-halide perovskites, capturing linear and non-linear effects and explaining optical anisotropy.

Contribution

The paper introduces a novel effective model incorporating spin-electromagnetic interactions for lead-halide perovskites, enabling analysis of both linear and non-linear optical properties.

Findings

The model accurately predicts the Verdet constant and refractive index.

Optical anisotropy arises from charge carrier hopping, not intrinsic material properties.

The model can be extended to study third-order non-linear optical effects like third-harmonic generation.

Abstract

We use general symmetry-based arguments to construct an effective model suitable for studying optical properties of lead-halide perovskites. To build the model, we identify an atomic-level interaction between electromagnetic fields and the spin degree of freedom that should be added to a minimally-coupled $\mathbf{k\cdot p}$ Hamiltonian. As a first application, we study two basic optical characteristics of the material: the Verdet constant and the refractive index. Beyond these linear characteristics of the material the model is suitable for calculating non-linear effects such as the third-order optical susceptibility. Analysis of this quantity shows that the geometrical properties of the spin-electric term imply isotropic optical response of the system, and that optical anisotropy of lead-halide perovskites is a manifestation of hopping of charge carriers. To illustrate this, we discuss third-harmonic generation.