Standing spin-wave mode structure and linewidth in partially disordered perpendicularly magnetized sub-micron Permalloy disc arrays

TL;DR

This study investigates how partial disorder in arrays of sub-micron Permalloy discs affects standing spin wave modes and linewidths, revealing disorder-dependent changes in resonance properties through broadband ferromagnetic resonance measurements.

Contribution

It provides the first experimental comparison of spin wave mode structures and linewidths in disordered arrays to theoretical models for isolated discs.

Findings

Demagnetizing parameters decrease with more disorder

Frequency difference between radial modes is higher than in isolated discs

Linewidths increase at low fields and with disorder

Abstract

Standing spin wave mode frequencies and linewidths in partially disordered perpendicular magnetized arrays of sub-micron Permalloy discs are measured using broadband ferromagnetic resonance and compared to analytical results from a single, isolated disc. The measured mode structure qualitatively reproduces the structure expected from the theory. Fitted demagnetizing parameters decrease with increasing array disorder. The frequency difference between the first and second radial modes is found to be higher in the measured array systems than predicted by theory for an isolated disc. The relative frequencies between successive spin wave modes are unaffected by reduction of the long-range ordering of discs in the array. An increase in standing spin wave resonance linewidth at low applied magnetic fields is observed and grows more severe with increased array disorder.