Polaritons de magnons em estruturas giromagnéticas com grafeno

Abstract

Electromagnetic waves propagating in magnetic crystals can couple with spin waves (magnons) excited in these materials, giving rise to hybrid modes known as magnon polaritons. These modes have been extensively studied in various materials and geometries due to their potential for technological applications in devices operating from the microwave to the far-infrared ranges. Recent studies have shown that the introduction of additional layers, especially graphene, can significantly modify the response of these systems, particularly under the influence of a static magnetic field with a specific orientation. In particular, when the field is applied perpendicular to the graphene layer, it excites the Landau levels of electrons on its surface, altering its conductivity and, consequently, the dynamics of the polaritons at the interface between media. In this work, we present a theoretical study on magnon polaritons in three distinct systems: a semi-infinite medium, a thin film, and a periodic superlattice. All structures are composed of gyromagnetic materials, each containing a single graphene layer at their interfaces, under the application of a magnetic field perpendicular to the interfaces. Our results reveal the emergence of new hybrid modes that are highly sensitive to tunable parameters, such as the magnetic field strength and the Fermi energy of the electrons in graphene.