Optimizing Spin Wave Nonreciprocity via Antenna-field Design

Spin wave nonreciprocity can arise either from spectral asymmetry, such as interfacial Dzyaloshinskii–Moriya interaction (DMI), or from an asymmetric excitation by an antenna’s near field. Here we show that the latter can be deterministically engineered by controlling the in-plane and out-of-plane Oersted components of a coplanar waveguide transducer by micromagnetic simulations. We derive a compact coupling formula that reveals an interference between the in-plane and out-of-plane Oersted field: neither component alone yields strong nonreciprocity, whereas their combination boosts nonreciprocity. Guided by this mechanism, we explore fabrication-ready designs that maximize nonreciprocity across practical field–frequency windows by tuning antenna height and signal line width/gap. The optimized device achieves substantial nonreciprocity without invoking DMI or special materials parameters, establishing a versatile foundation for directional magnonic components.