Reprogrammable magnonic band structure of layered Permalloy/Cu/Permalloy nanowires

TL;DR

This paper demonstrates that the magnonic band structure in layered Permalloy/Cu/Permalloy nanowires can be reprogrammed by changing the relative magnetization orientation of the layers, enabling magnetic field-controlled reconfigurable magnonic devices.

Contribution

It introduces a method to reprogram magnonic band structures in layered nanowires based on magnetic orientation, supported by experimental and microscopic analysis.

Findings

Parallel layers show two dispersive modes with positive and negative group velocities.

Anti-parallel layers exhibit only one dispersive mode with positive group velocity.

Mode hybridization explains the reprogrammability of the magnonic band structure.

Abstract

Reprogrammability of magnonic band structure in layered Permalloy/Cu/Permalloy nanowires is demonstrated to depend on the relative orientation of the two layers magnetization. By using Brillouin light spectroscopy, we show that when the layers are aligned parallel two dispersive modes, with positive and negative group velocity, are observed while when the magnetic layers are aligned anti-parallel, only one dispersive mode, with positive group velocity, is detected. Our findings are successfully compared and interpreted in terms of a microscopic (Hamiltonian-based) method. An explanation for the observed behavior can be attributed to mode-mixing (or hybridization) effect when the two magnetic layers are aligned anti-parallel. This work opens the path to magnetic field-controlled reconfigurable magnonic crystals with multi-modal frequency transmission characteristics.