Inverse-design of two-dimensional magnonic crystals via topology optimization with frequency-domain micromagnetics

TL;DR

This paper presents an inverse-design framework using genetic algorithms and frequency-domain micromagnetics to discover novel two-dimensional magnonic crystal structures with large band gaps, advancing the design of spintronic metamaterials.

Contribution

It introduces a novel inverse-design method combining global optimization and micromagnetic simulations to identify unconventional magnonic crystal geometries with large band gaps.

Findings

Successfully discovered new MC designs with large band gaps.

Validated designs with time-domain micromagnetic simulations.

Found increased non-convexity in design landscape at higher bands.

Abstract

Magnonic crystals (MCs) are emerging spintronic metamaterials capable of manipulating transmission properties of magnons, the quanta of spin waves. Due to the complex relationship between lattice geometry and magnonic band dispersion, it remains challenging to establish general design strategies for optimizing targeted properties in MCs. In this study, we demonstrated an inverse-design framework for two-dimensional MCs to explore unconventional lattice structures with large magnonic band gaps. We employed genetic algorithms to enable global exploration of structures with a complete band gap as the objective property, and used frequency-domain micromagnetic simulations for computationally efficient band gap evaluation. Our established inverse-design method successfully discovered several previously unreported designs of MCs, whose performance was validated using time-domain micromagnetic simulations. Furthermore, we observed that the design landscape becomes increasingly non-convex at high-order bands, suggesting the existence of multiple design solutions. The overall inverse-design framework is expected to be broadly applicable to experimentally accessible material systems and device dimensions, facilitating the formulation of design rules for MCs.