Propagating spin wave spectroscopy of Permalloy thin films. Effects of nanogrooves and constrictions

Abstract

With the aim of contributing to the advancement and development of the emerging field of spin wave optics, we investigate the propagation of magnetostatic surface spin waves in a uniform permalloy waveguide with grooves and constrictions created by in-situ atomic force microscopy nanolithography. Our findings reveal that the introduction of these artificial defects in the spin waves path leads to an unexpected reduction in the signal intensity of the transmitted spin wave compared with a waveguide interrupted by a full slit. This remarkable extinction phenomenon dominates the tunnel-like propagation facilitated by magnetic dipolar coupling across the gap. Combining experimental and numerical analyses, the complex interplay between spin wave tunneling, diffraction and reflection at the edges of the waveguide is comprehensibly addressed. These results provide new insights into the controllable manipulation of spin waves, opening up promising avenues for the development of spin wave switches and interferometers.