Topological magnetoelectric effects in microwave far-field radiation

TL;DR

This paper demonstrates the observation of topological magnetoelectric effects in microwave far-field radiation using a ferrite resonator, revealing complex field structures and localized energy regions.

Contribution

It introduces the first experimental observation of topological ME effects in microwave far-field radiation with a ferrite resonator, highlighting unique field configurations.

Findings

Microwave far-field radiation exhibits torsion structures with varying electric and magnetic field angles.

Localized regions of ME energy are observed in the far field.

Fields possess topological properties distinct from free space electromagnetic fields.

Abstract

Similar to electromagnetism, described by the Maxwell equations, the physics of magnetoelectric (ME) phenomena deals with the fundamental problem of the relationship between electric and magnetic fields. Despite a formal resemblance between the two notions, they concern effects of different natures. In general, ME coupling effects manifest in numerous macroscopic phenomena in solids with space and time symmetry breakings. Recently it was shown that the near fields in the proximity of a small ferrite particle with magnetic dipolar mode (MDM) oscillations have the space and time symmetry breakings and topological properties of these fields are different from topological properties of the free space electromagnetic (EM) fields. Such MDM originated fields, called magnetoelectric (ME) fields, carry both spin and orbital angular momentums. They are characterized by power flow vortices and non zero helicity. In this paper, we report on observation of the topological ME effects in far field microwave radiation based on a small microwave antenna with a MDM ferrite resonator. We show that the microwave far-field radiation can be manifested with a torsion structure where an angle between the electric and magnetic field vectors varies. We discuss the question on observation of the regions of localized ME energy in far field microwave radiation.