Unidirectional magnetoelectric-field multiresonant tunneling

TL;DR

This paper demonstrates unidirectional multiresonant tunneling of magneto-electric fields in microwave structures, revealing topological properties and Fano-resonance effects that differ with magnetic field direction.

Contribution

It introduces the concept of unidirectional ME-field tunneling linked to topological properties and Fano resonances in microwave structures with ferrite disks.

Findings

Unidirectional ME-field tunneling depends on magnetic field direction.

Fano-resonance peaks indicate resonant tunneling states.

Topological edge currents influence ME-field propagation.

Abstract

Unidirectional multi-resonant tunneling of the magneto-electric (ME)-field excitations through a sub wavelength (regarding the scales of regular electromagnetic radiation) vacuum or isotropic-dielectric regions has been observed in two-port microwave structures having a quasi-2D ferrite disk with magnetic-dipolar-mode (MDM) oscillations. The excitations manifest themselves as the Fano-resonance peaks in the scattering-matrix parameters at the stationary states of the MDM spectrum. The ME near-field excitations are quasi magnetostatic fields with non-zero helicity parameter. Topological-phase properties of ME fields are determined by edge chiral currents of MDM oscillations. We show that while for a given direction of a bias magnetic field (in other words, for a given direction of time), the ME-field excitations are considered as forward tunneling processes, in the opposite direction of a bias magnetic field (the opposite direction of time), there are backward tunneling processes. Unidirectional ME-field resonant tunneling is observed due to distinguishable topology of the forward and backward ME-field excitations. We establish a close connection between the Fano-resonance unidirectional tunneling and topology of ME fields in different microwave structures.