[en] The propagation of magnetostatic surface spin waves (MSSWs) in nanopatterned permalloy waveguides is explored to advance the field of spin-wave optics. Using Atomic Force Microscopy nanolithography and Focused Ion Beam etching, grooves and constrictions were introduced into the waveguides, revealing a surprising non-monotonic reduction in transmitted spin-wave intensity as the waveguide cross-section narrows, as evidenced in Fig. 1. Remarkably, narrower grooves induce stronger signal extinction compared to complete gaps, where the MSWSs transmits solely by dipolar coupling from one edge to the other. Experimental and numerical analyses unravel the intricate interplay of spin-wave diffraction, tunneling, and edge reflections, uncovering a transverse-mode variation responsible for this phenomenon. These findings might be instrumental in the continuous quest for enhanced control of spin-wave propagation, offering novel strategies for developing spin-wave switches, interferometers, and graded-index magnonic devices.
