Interplay between intra- and inter-nanowires dynamic dipolar interactions in the spin wave band structure of Py/Cu/Py nanowires

TL;DR

This study investigates how intra- and inter-nanowire dipolar interactions influence the spin wave band structure in reprogrammable Py/Cu/Py nanowire arrays, revealing magnetic configurations and collective magnonic behaviors relevant for nanoscale spintronic devices.

Contribution

It provides a combined experimental and theoretical analysis of reprogrammable spin wave band structures in layered nanowire arrays, highlighting the role of dipolar interactions and magnetic configurations.

Findings

Anti-parallel magnetization configuration is stabilized in specific magnetic field ranges.

Collective spin waves propagate with different bandwidths depending on interactions.

Phase relations determine whether spin waves are stationary or propagating.

Abstract

We have studied both experimentally and theoretically the reprogrammable spin wave band structure in Permalloy(10nm)/Cu(5nm)/Permalloy(30nm) nanowire arrays of width w=280 nm and inter-wire separation in the range from 80 to 280 nm. We found that, depending on the inter-wire separation, the anti-parallel configuration, where the magnetizations of the two Permalloy layers point in opposite directions, is stabilized over specific magnetic field ranges thus enabling us to directly compare the band structure with that of the parallel alignment. We show that collective spin waves of the Bloch type propagate through the arrays with different magnonic bandwidths as a consequence of the interplay between the intra- and inter-nanowire dynamic dipolar interactions. A detailed understanding, e.g. whether they have a stationary or propagating character, is achieved by considering the phase relation (in-phase or out-of-phase) between the dynamic magnetizations in the two ferromagnetic layers and their average value. This work opens the path to magnetic field-controlled reconfigurable layered magnonic crystals that can be used for future nanoscale magnon spintronic devices.