Graded Index Confined Spin Waves in an Intermediate Domain Wall

TL;DR

This paper introduces a mathematical model for confined spin wave modes in magnetic domain walls, demonstrating how local wall angle and excitation frequency influence wave propagation, supported by micromagnetic simulations.

Contribution

The paper presents a new analytical model for propagating confined spin waves in intermediate domain walls, linking local wall geometry and frequency to wave behavior.

Findings

Model predicts local wavenumber dependence on wall angle and frequency

Micromagnetic simulations confirm the model's accuracy

Insights into spin wave behavior in curved and finite structures

Abstract

We propose a mathematical model for describing propagating confined modes in domain walls of intermediate angle between domains. The proposed model is derived from the linearised Bloch equations of motion and after reasonable assumptions, in the scenario of a thick enough magnetic patch, are accounted. The model shows that there is a clear dependence of the local wavenumber of the confined spin wave on the local angle of the wall and excitation frequency used, which leads to the definition of a local index of refraction in the wall as a function of such angle and frequency. Therefore, the model applies to 1-D propagating modes, although it also has physical implications for 2-D scenarios where a domain wall merges with a saturated magnetic region. Micromagnetic simulations are in good agreement with the predictions of the model and also give insight on the effects of curved finite structures may have on the propagating characteristics of spin waves in domain walls.