High frequency magnetic behavior through the magnetoimpedance effect in CoFeB/(Ta, Ag, Cu) multilayered ferromagnetic thin films

TL;DR

This study investigates the magnetoimpedance effect in CoFeB/(Ta, Ag, Cu) multilayered thin films, revealing how different non-magnetic layers influence magnetic resonance and impedance behavior across frequencies.

Contribution

It provides new insights into how the choice of non-magnetic metal layers affects magnetoimpedance and resonance frequencies in multilayered ferromagnetic thin films.

Findings

FMR significantly influences magnetoimpedance at ~470 MHz in CoFeB/Cu multilayers.

Different non-magnetic metals shift the impedance maximum frequency.

Impedance variation ranges from 25% to 30% depending on the metal layer.

Abstract

We studied the dynamics of magnetization through an investigation of the magnetoimpedance effect in CoFeB/(Ta, Ag, Cu) multilayered thin films grown by magnetron sputtering. Impedance measurements were analyzed in terms of the mechanisms responsible for their variations at different frequency intervals and the magnetic and structural properties of the multilayers. Analysis of the mechanisms responsible for magnetoimpedance according to frequency and external magnetic field showed that for the CoFeB/Cu multilayer, ferromagnetic resonance (FMR) contributes significantly to the magnetoimpedance effect at frequencies close to 470 MHz. This frequency is low when compared to the results obtained for CoFeB/Ta and CoFeB/Ag multilayers and is a result of the anisotropy distribution and non-formation of regular bilayers in this sample. The MImax values occurred at different frequencies according to the used non-magnetic metal. Variations between 25% and 30% were seen for a localized frequency band, as in the case of CoFeB/Ta and CoFeB/Ag, as well as for a wide frequency range, in the case of CoFeB/Cu.