Control of site occupancy by variation of the Zn and Al content in NiZnAl ferrite epitaxial films with low magnetic damping

TL;DR

This study demonstrates how varying Zn and Al content in NiZnAl ferrite epitaxial films allows control over their structural and magnetic properties, with implications for low-damping magnetic applications.

Contribution

It introduces a method to tune magnetic damping and properties in NiZnAl ferrite films by adjusting Zn and Al content during epitaxial growth.

Findings

Zn content affects magnetic properties significantly

Al content influences strain and magnetic behavior more strongly

Identified a minimum in g-factor and linewidth as a function of film thickness

Abstract

The structural and magnetic properties of Zn/Al doped nickel ferrite thin films can be adjusted by changing the Zn and Al content. The films are epitaxially grown by reactive magnetron sputtering using a triple cluster system to sputter simultaneously from three different targets. Upon the variation of the Zn content the films remain fully strained with similar structural properties, while the magnetic properties are strongly affected. The saturation magnetization and coercivity as well as resonance position and linewidth from ferromagnetic resonance (FMR) measurements are altered depending on the Zn content in the material. The reason for these changes can be elucidated by investigation of the x-ray magnetic circular dichroism spectra to gain site and valence specific information with elemental specificity. Additionally, from a detailed investigation by broadband FMR a minimum in g-factor and linewidth could be found as a function of film thickness. Furthermore, the results from a variation of the Al content using the same set of measurement techniques is given. Other than for Zn, the variation of Al affects the strain and even more pronounced changes to the magnetic properties are apparent.