Tailoring crosstalk between localized 1D spin-wave nanochannels using focused ion beams

TL;DR

This study demonstrates precise control of localized spin-wave modes in 1D Permalloy nanochannels using focused ion beam techniques, enabling tunable magnonic device functionalities through edge and gap modifications.

Contribution

It introduces a method to tailor crosstalk in 1D spin-wave nanochannels via focused ion beams, enabling localized mode control and frequency tuning.

Findings

Edge modes are observed after ion irradiation trimming.

Localized modes at inner edges emerge after microstrip milling.

Mode frequencies can be tuned up to 5 GHz by adjusting separation.

Abstract

1D spin-wave conduits are envisioned as nanoscale components of magnonics-based logic and computing schemes for future generation electronics. `A-la-carte methods of versatile control of the local magnetization dynamics in such nanochannels are highly desired for efficient steering of the spin waves in magnonic devices. Here, we present a study of localized dynamical modes in 1-$\mu$m-wide Permalloy conduits probed by microresonator ferromagnetic resonance technique. We clearly observe the lowest-energy edge mode in the microstrip after its edges were finely trimmed by means of focused Ne$^+$ ion irradiation. Furthermore, after milling the microstrip along its long axis by focused ion beams, creating consecutively $\sim$50 and $\sim$100 nm gaps, additional resonances emerge and are attributed to modes localized at the inner edges of the separated strips. To visualize the mode distribution, spatially resolved Brillouin light scattering microscopy was used showing an excellent agreement with the ferromagnetic resonance data and confirming the mode localization at the outer/inner edges of the strips depending on the magnitude of the applied magnetic field. Micromagnetic simulations confirm that the lowest-energy modes are localized within $\sim$15-nm-wide regions at the edges of the strips and their frequencies can be tuned in a wide range (up to 5 GHz) by changing the magnetostatic coupling (i.e. spatial separation) between the microstrips.