In this paper, we have demonstrated a detailed study of Electromagnetic interaction with a biased gyromagnetic medium. Our key contributions in this paper are 

• For the first time, we categorized the topology classes of isofrequency surfaces and identified the connection between the evolution of the isofrequency surface topology with the gyrotropicity of the medium.

• We revealed the relation between photonic-spin and the isofrequency topology.

• The existence of cutoff-less waveguide modes is shown in the paper, owing to the hyperbolic isofrequency surface topology. This paves the way for extremely small guided structures.

• A new type of cut-off for the waveguide mode is revealed, which we call gyrotropy-induced cut-off. This cut-off manifests as a result of interaction between the material-induced and structure-induced photonic spins. 

This paper got published online in Physical Review A on 25th February 2022.

This work focuses on the impact of three diagonal permeability terms having independent variation with frequency in antiferromagnets. Our key contributions in this paper are 

• We classified the six propagation regimes corresponding to discrete isofrequency surface topologies in antiferromagnets. We also mentioned the regime boundaries.  

• We highlighted the special frequency regime, which allows propagation only because of a strong gyrotropic medium.

• We show the photonic spin profile over the ellipsoidal isofrequency surface corresponding to this special regime.

• In an antiferromagnet-filled waveguide, we show how extreme squinting of one of the photonic spin senses, which leads to an anomalous Poynting vector across the cross-section of the waveguide. 

This paper got accepted for oral presentation at the Asia-Pacific Microwave Conference 2022, Yokohama, Japan.