Temperature Dependence of Spin Pinning and Spin-Wave Dispersion in Nanoscopic Ferromagnetic Waveguides

The field of magnonics attracts significant attention due to the possibility of utilizing information coded into the spin-wave phase or amplitude to perform computation operations on the nanoscale. Recently, spin waves were investigated in Yttrium Iron Garnet (YIG) waveguides with widths down to 50 nm and aspect ratios of thickness to width approaching unity. A critical width was found, below which the exchange interaction suppresses the dipolar pinning phenomenon, and the system becomes unpinned. Here, we continue these investigations and analyze the pinning phenomenon and spin-wave dispersion as functions of temperature, thickness, and material parameters. Higher order modes, the influence of a finite wavevector along the waveguide, and the impact of the pinning phenomenon on the spin-wave lifetime are discussed, as well as the influence of a trapezoidal cross-section and edge roughness of the waveguide. The presented results are of particular interest for potential applications in magnonic devices and the incipient field of quantum magnonics at cryogenic temperatures.