Optical Hall effect in strained graphene

TL;DR

This paper proposes a novel method to induce optical Hall conductivity in graphene through strain engineering, eliminating the need for magnetic fields, and predicts tunable effects in 2D materials for advanced opto-electro-mechanical applications.

Contribution

It introduces strain as a means to generate optical Hall effects in graphene, expanding the potential for device applications without magnetic fields.

Findings

Strain induces a finite optical Hall conductivity in graphene.

The optical Hall effect can be tuned by strain amplitude and direction.

Predictions extend to other 2D materials with similar effects.

Abstract

When passing an optical medium in the presence of a magnetic field, the polarization of light can be rotated either when reflected at the surface (Kerr effect) or when transmitted through the material (Faraday rotation). This phenomenon is a direct consequence of the optical Hall effect arising from the light-charge carrier interaction in solid state systems subjected to an external magnetic field, in analogy with the conventional Hall effect. The optical Hall effect has been explored in many thin films and also more recently in 2D layered materials. Here, an alternative approach based on strain engineering is proposed to achieve an optical Hall conductivity in graphene without magnetic field. Indeed, strain induces lattice symmetry breaking and hence can result in a finite optical Hall conductivity. First-principles calculations also predict this strain-induced optical Hall effect in other 2D materials. Combining with the possibility of tuning the light energy and polarization, the strain amplitude and direction, and the nature of the optical medium, large ranges of positive and negative optical Hall conductivities are predicted, thus opening the way to use these atomistic thin materials in novel specific opto-electro-mechanical devices.