# Electrically controlled terahertz magneto-optical phenomena in continuous and patterned graphene

## TL;DR

This paper demonstrates that in graphene, magnetic circular dichroism and Faraday rotation in the terahertz range can be electrically controlled and inverted via electrostatic doping, with patterned graphene showing strong magneto-plasmonic resonances.

## Contribution

It introduces a method to electrically modulate and invert magneto-optical effects in graphene at terahertz frequencies, including patterned structures with resonant enhancements.

## Key findings

- Magnetic circular dichroism and Faraday rotation can be tuned and inverted in graphene using electrostatic doping.
- Patterned graphene antidots exhibit strong magneto-plasmonic resonances in the terahertz range.
- Electrostatic control enables non-reciprocal polarization effects without changing magnetic field orientation.

## Abstract

The magnetic circular dichroism and the Faraday rotation are the fundamental phenomena of great practical importance arising from the breaking of the time reversal symmetry by a magnetic field. In most materials the strength and the sign of these effects can be only controlled by the field value and its orientation. Furthermore, the terahertz range is lacking materials having the ability to affect the polarisation state of the light in a non-reciprocal manner. Here we demonstrate, using broadband terahertz magneto-electro-optical spectroscopy, that in graphene both the magnetic circular dichroism and the Faraday rotation can be modulated in intensity, tuned in frequency and, importantly, inverted using only electrostatic doping at a fixed magnetic field. In addition, we observe strong magneto-plasmonic resonances in a patterned array of graphene antidots, which potentially allows exploiting these magneto-optical phenomena in a broad THz range.