Magnetoimpedance effect at the high frequency range for the thin film geometry: Numerical calculation and experiment

Abstract

The magnetoimpedance effect is a versatile tool to investigate ferromagnetic materials, revealing aspects on the fundamental physics associated to magnetization dynamics, broadband magnetic properties, important issues for current and emerging technological applications for magnetic sensors, as well as insights on ferromagnetic resonance effect at non-saturated magnetic states. Here, we perform a theoretical and experimental investigation of the magnetoimpedance effect for the thin film geometry in a wide frequency range. We calculate the longitudinal magnetoimpedance for single layered, multilayered or exchange biased systems from an approach that considers a magnetic permeability model for planar geometry and the appropriate magnetic free energy density for each structure. From numerical calculations and experimental results found in literature, we analyze the magnetoimpedance behavior, and discuss the main features and advantages of each structure. To test the robustness of the approach, we directly compare theoretical results with experimental magnetoimpedance measurements obtained in a wide range of frequencies for an exchange biased multilayered film. Thus, we provide experimental evidence to confirm the validity of the theoretical approach employed to describe the magnetoimpedance in ferromagnetic films, revealed by the good agreement between numerical calculations and experimental results.

Asymmetric magnetoimpedance effect in ferromagnetic multilayered biphase films

“…The MI measurements present a frequency dependent shift, a feature related to the electrical/metallic contributions of the sample and of the microwave cavity or microstrip employed in the experiment [16].…”

Mirroring the dynamic magnetic behavior of magnetostrictive Co/(Ag,Cu,Ta) multilayers grown onto rigid and flexible substrates

“…This fact is evidenced by the displacement of the peaks position toward higher fields H as the frequency f increases [28]. Moreover, the precise frequency limits between low/moderate and high frequency regimes can be verified using the method described by Barandiarán et al [29], and previously employed by our group [30].…”

Exploring the magnetization dynamics of NiFe/Pt multilayers in flexible substrates

“…This feature reflects the fact that the skin effect is the main responsible for the MI variations [18]. Beyond $0.85 GHz, the displacement of the peaks position toward higher magnetic field values suggests that the strong skin effect and the FMR effect become the main mechanisms responsible for the MI variations.…”