Magnetization pinning in conducting films demonstrated using broadband ferromagnetic resonance

TL;DR

This study uses broadband ferromagnetic resonance to detect and characterize a magnetically depleted sub-layer in thin Permalloy films, revealing inhomogeneities not observable with conventional methods.

Contribution

It demonstrates a novel application of broadband FMR for detecting magnetic inhomogeneities in conducting films, including a previously unidentifiable sub-layer.

Findings

Detection of a magnetically depleted top sub-layer in Permalloy films.

Confirmation of the sub-layer's properties via Brillouin light scattering.

Reproducibility of the effect across multiple films with thicknesses 30-100nm.

Abstract

The broadband microstrip ferromagnetic resonance technique has been applied for detection and characterization of a magnetic inhomogeneity in a film sample. In the case of a 100nm thick Permalloy film an additional magnetically depleted top sub-layer, practically unidentifiable by the conventional ferromagnetic resonance setup, has been detected and characterized. These results have been confirmed by Brillouin light scattering spectroscopy revealing the fact that the optical properties of the additional sub-layer do not differ much from those of the bulk of the film. Subsequent characterization of a large number of other presumably single-layer films with thicknesses in the range 30-100nm using the same ferromagnetic resonance technique also revealed the same effect.