Improvement of measured precision on complex permeability of magnetic thin films via optimizing the post data processing method

Abstract

Magnetic thin films with excellent high frequency characteristics are widely used in various fields of high-speed electronics. Different properties are required for magnetic thin film using in different applications. The complex permeability spectrum of a magnetic thin film is among the most important factors determining the suitability of a magnetic thin film for an application and the performances of the devices made from the magnetic thin film. The measurement of the complex permeability of thin films is supposed to be urgent and crucial for both materials scientists and application engineers [1-3]. Bekker [4] and Liu [5] developed a one-port strip line permeameter and this method is widely used by researcher. An analytical calculation procedure with an adaptive error correction was used to deduce the complex permeability of a ferromagnetic film material in the 0.05–5GHz frequency range with good accuracy. However, the method can bring some inevitable error in high frequencies because the proportionality factor k is established by adjusting the initial permeability at low frequencies, which determined by the saturation magnetization (4πM s ) and the in-plane uniaxial anisotropy field (H k ) of thin films [4-5]. In this article, we presented an improved measurement technique and optimized post data processing method for determining the broadband complex permeability of magnetic thin films. The frequency-dependant proportionality factor k was simulated and the measured results fit well with the Landau-Lifchitz-Gilbert theory.