An energy harvesting technology controlled by ferromagnetic resonance

Yuta Nogi,Yoshio Teki,Eiji Shikoh

doi:10.1063/5.0056724

Abstract

We have successfully demonstrated electrical charging using the electromotive force (EMF) generated in a ferromagnetic metal (FM) film under ferromagnetic resonance (FMR). In the case of Ni80Fe20 films, electrical charge due to the EMF generated under FMR can be accumulated in a capacitor; however, the amount of charge is saturated well below the charging limit of the capacitor. Meanwhile, in the case of Co50Fe50, electrical charge generated under FMR can be accumulated in a capacitor and the amount of charge increases linearly with the FMR duration time. The difference between the Ni80Fe20 and Co50Fe50 films is due to the respective magnetic field ranges for the FMR excitation. When the FM films were in equivalent thermal states during FMR experiments, Co50Fe50 films could maintain FMR in a detuned condition, while Ni80Fe20 films were outside the FMR excitation range. The EMF generation phenomenon in an FM film under FMR can be used as an energy harvesting technology by appropriately controlling the thermal conditions of the FM film.

Highlights

While the output voltage per ferromagnetic metal (FM) film is much small, if it is possible to catch a microwave energy through the ferromagnetic resonance (FMR) excitation and to use a series connection consisting of various FM films with different FMR conditions, in principle, the electromotive force (EMF) can be generated in all frequency ranges of microwaves because this generated EMF under FMR is a DC voltage
We have successfully demonstrated electrical charging using the EMF generated in an FM film itself under the FMR and show that the EMF generation phenomenon under the FMR is usable as an energy harvesting technology with appropriate control of the thermal conditions of the FM film
To evaluate the electric charging properties under the FMR, the electrical circuit shown in Fig. 1(b) was connected to the FM film sample, in place of the nanovoltmeter used for the above EMF confirmation

Summary

Introduction

The electrical current derived from the EMF generated in the FM film under the FMR flowed and the electric charges were accumulated in the capacitor for the FMR duration time. Using the charging circuit, the electric current generated in the FM films under the respective FMR condition to satisfy Eq (1) flows and the capacitor is charged.

Results

Conclusion