A broadband method to measure magnetic spectra of thin films

Abstract

Conventional single-port strip-line techniques to measure permeability of thin films are based on the quasistationary approximation. In this paper, wave phenomena in the measurement cell are taken into account. Particularly, the dielectric response of the sample may be accounted for and removed by the consideration of the geometry of the cell and the sample. An additional measurement with a reference sample with known constitutive parameters allows the directivity error and the frequency response error to be removed from the experimental reflectivity data; accounting for the field inhomogeneity inside the strip cell is also introduced. A proper selection of the reference sample is shown to be critical for the measurement accuracy. The measurement results may also be affected by the demagnetization of the sample. With these corrections introduced, the operating frequency range of the technique is extended up to 8GHz. The measurement results are validated by the data obtained with either standard materials or by conventional techniques.

Measure the Complex Permeability of Ferromagnetic Thin Films: Comparison Shorted Microstrip Method With Microstrip Transmission Method

“…However, this technique is ill suited for conductive materials, particularly when the sample under study is a low-resistive film [1]. For metal films deposited on a flexible polymer substrate, coaxial line perturbation method has good performance [2].…”

Control over magnetic spectrum of multilayer magnetic film metamaterial

“…The effective permeability of both samples is measured with a stripline permeameter 17 in the frequency range of 0.13 to 4 GHz.…”

The Study of Structure-Dependent Properties of Thin Magnetic Films at Microwaves by Field-Domain Resonance Technique

“…The problem is that the measured washer samples are usually wound of film stripes, therefore the coaxial measurements are limited to flexible substrates and the obtained data are distorted by magnetostriction [5,6,10,11]. The stripe cells are calibrated less accurately and the measurements inherit the problems of radiation into surrounding space [4,7].…”

“…The SB-FMR technique is much more sensitive [2,3], the sample is uniformly magnetised but the calculated permeability data may differ from that ones obtained under zero bias and the technique is poorly suited for measurements within a range of frequencies. The SF-VNA measurements are performed under non-zero external bias as well [5,6], but the sensitivity of SF-VNA technique is much lower than that of SB-FMR one even in case of the resonance enhancement [7] as the measurement errors (the signal to noise ratio, SNR) are defined by calibration accuracy of a measurement cell [4]. The SF-VNA measurements are usually performed either in a coaxial line or in a strip-line.…”

“…For the characterisation of microwave permeability of metal films two measurement techniques are frequently used: the sweep-frequency measurements of permittivity/permeability spectra of laminated samples with the help of vector network analysers (SF-VNA technique) and the conventional ferromagnetic resonance fixed frequency/sweep bias measurements (SB-FMR technique) that are usually performed in a high-quality cavity [1][2][3][4]. The SF-VNA technique is popular as it is fast and simple and the obtained permittivity/permeability data can be directly used in the engineering practice, but the samples under study are relatively large and unsaturated.…”