Line Waves at the Interface of Magneto-Electric Boundaries

Line waves (LWs) are exceptional electromagnetic (EM) modes found at the junctions of impedance surfaces, satisfying either electromagnetic duality or the parity-time symmetry. To date, the implementation of LWs has been limited primarily to employing electric impedance surfaces. In our study, we unveil that a planar junction between an electric impedance surfaces, and a magnetic media sustains the LW exhibiting backscattering-immune transportation. The entirely magnetic media ( <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" alttext="ε=1" display="inline"><m:mrow><m:mi>ϵ</m:mi><m:mo>=</m:mo><m:mn>1</m:mn></m:mrow></m:math> , and <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" alttext="μ≠ 1" display="inline"><m:mrow><m:mi>μ</m:mi><m:mo>≠</m:mo><m:mn>1</m:mn></m:mrow></m:math> ) supports TE-polarized surface magnon polaritons while we tailor the electric surface impedance to support TM-polarized surface waves. Remarkably, the envisioned line-wave waveguide emerges as a pseudospin-filtered channel, facilitating a uni-dimensional wave generated through the synergistic interplay of two surface waves possessing perpendicular polarizations. Our theoretical findings, corroborated by simulations, unveil a new type of polaritonic wave characterized by remarkably confined properties. This discovery holds promise for manipulating light on the nanoscale, opening avenues for the implementation of magneto-electric pseudospin-polarized waveguide.