Spin-wave nonreciprocity based on interband magnonic transitions

We theoretically demonstrate linear spin-wave nonreciprocity in a Ni80Fe20 nanostripe waveguide, based on interband magnonic transitions induced by a time-reversal and spatialinversion symmetry breaking magnetic field. An analytical coupled-mode theory of spin waves, developed to describe the transitions which are accompanied by simultaneous frequency and wavevector shifts of the coupled spin waves, is well corroborated by numerical simulations. Our findings could pave the way for the realization of spin-wave isolation and the dynamic control of spin-wave propagation in nanoscale magnonic integrated circuits via an applied magnetic field.