Study on High-Frequency 3–D Magnetization Precession Modes of Circular Magnetic Nano-Dots Using Coplanar Wave Guide Vector Network Analyzer Ferromagnetic Resonance

Abstract

Ferromagnetic resonance (FMR) modes for Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">70</sub> Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30</sub> magnetic nano-dots of 100 nm in diameter in a mono-domain state are studied under different in-plane and out-of-plane magnetic fields using a reflection measurement from a vector network analyzer with a coplanar wave guide (CPW VNA FMR) and a micromagnetics simulation. The observed real and imaginary parts of the reflection signal become a combination of symmetric and antisymmetric Lorentzian forms in FMR. The combinations are given different susceptibility components of χ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xx</sub> and χ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zx</sub> by changing the sample position on the CPW. The magnetic dots exhibit triple modes in FMR spectra from an influence of the demagnetization field distribution in the mono-domain state. The magnetic dots also show a different variation of FMR amplitude in χ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xx</sub> and χ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zx</sub> for an out-of-plane field increase.