Spin-wave signal rejection in magnonic waveguides induced by conducting films with a single groove

Abstract

In this work, we explore the formation of transmission gaps in wave spectra of a ferrite film covered by a thin vanadium dioxide (VO2) stripe with a single groove on its surface. It was found that this waveguide does not manifest noticeable spin-wave reflections, but still demonstrates rejection bands in its transmission characteristic. This is due to a finite drop of spin-wave group velocity in a wide frequency range affected by the conducting VO2 layer with a smooth profile inhomogeneity. The main feature of the proposed waveguides is a short groove length required for the formation of spectral regions with enhanced spin-wave signal rejection. Namely, the utilization of a groove with a length of 66 µm results in a pronounced rejection band with a depth of 10 dB and a width of 19 MHz. To achieve these values in conventional magnonic crystals, several millimeters of a periodic array of reflectors are required. Therefore, we believe that the obtained findings pave a clear way forward for microminiaturizing spin-wave devices, where features of magnonic crystals are exploited.