Microwave-induced DC Signal in a Permalloy Thin Strip at Low Applied Magnetic Field

TL;DR

This study explores microwave-induced DC signals in a permalloy thin strip at low magnetic fields, revealing unique resonance behaviors and proposing a model highlighting the role of shape anisotropy in signal distortion.

Contribution

It presents the first detailed analysis of low-field ferromagnetic resonance signals in permalloy strips and introduces a quantitative model accounting for shape anisotropy effects.

Findings

Resonant signals differ significantly between low and high magnetic fields.

Shape anisotropy plays a crucial role in magnetization and signal distortion.

A new model explains the observed low-field resonance phenomena.

Abstract

We investigated the ferromagnetic resonance signals in a polycrystalline permalloy thin strip under in-plane low static magnetic field. A series of DC voltages, which contain ferromagnetic resonance or spin wave resonance signals, were measured by inducing microwave frequencies greater than 10 gigahertz. The resonant signals measured in low magnetic field show different properties from those detected in high field condition. Based on the theory of DC effects in ferromagnetic resonance and the experimental data of anisotropic magnetoresistance, a quantitative model was proposed. We found that the shape anisotropy significantly affects magnetization, and distorts the resonant signals in low field condition.