Magnetic Composites: Magnonic Excitations vs. Three-Dimensional Structural Periodicity

TL;DR

This paper investigates the spin wave spectrum in a 3D periodic magnetic composite with ferromagnetic grains in a lattice, revealing frequency gaps sensitive to material contrasts and structural parameters.

Contribution

It demonstrates the existence of magnonic band gaps in a 3D periodic magnetic structure and analyzes their dependence on material and structural contrasts.

Findings

Identification of forbidden frequency regions for magnon propagation.

Magnetic band gaps are sensitive to exchange and magnetization contrasts.

Widths of magnonic gaps depend on structural parameters.

Abstract

This study deals with the spin wave spectrum in magnetic macrostructure (composed of two ferromagnetic materials) showing a 3D periodicity: spherical ferromagnetic grains disposed in the nodes of a simple cubic crystal lattice are embedded in a matrix with different ferromagnetic properties. It is shown that the \textit{magnonic spectrum} of this composite structure exhibits frequency regions \textit{forbidden} for magnon propagation, and the energy gaps are found to be sensitive to the exchange contrast between the constituent materials as well as to the magnetization contrast. The widths of the respective magnonic gaps are studied as functions of parameters characterizing the magnetic structure.