Tunable Magnonic Frequency and Damping in [Co/Pd]8 Multilayers with Variable Co Layer Thickness

TL;DR

This study investigates how the magnetization precession frequency and damping in [Co/Pd]8 multilayers can be tuned by varying the Co layer thickness, revealing a systematic relationship relevant for spintronics and magnonic applications.

Contribution

It provides experimental data on the tunability of frequency and damping in multilayers with perpendicular magnetic anisotropy based on Co layer thickness variations.

Findings

Precession frequency varies from 5 GHz to 90 GHz with Co thickness.

Damping coefficient inversely proportional to Co thickness.

Linear relation between magnetic anisotropy and damping coefficient.

Abstract

We report the experimental observation of collective picosecond magnetization dynamics in [Co/Pd]8 multilayers with perpendicular magnetic anisotropy. The precession frequency shows large and systematic variation from about 5 GHz to about 90 GHz with the decrease in the Co layer thickness from 1.0 nm to 0.22 nm due to the linear increase in the perpendicular magnetic anisotropy. The damping coefficient 'alpha' is found to be inversely proportional to the Co layer thickness and a linear relation between the perpendicular magnetic anisotropy and 'alpha' is established. We discuss the possible reasons behind the enhanced damping as the d-d hybridization at the interface and spin pumping. These observations are significant for the applications of these materials in spintronics and magnonic crystals.