Improved accuracy thin film permeability extraction for a microstrip permeameter

Abstract

It is shown using full-wave simulations that several of the conventional assumptions made for extracting permeability data from a microstrip permeameter are not justified. In particular, the proportionality between the measured effective permeability in the device and the true permeability of the film is not a constant. It is a function of the permeability of the film, its geometry and the dimensions of the microstrip permeameter. A model exploiting the analyticity of the function relating effective to true permeability is used to derive this proportionality function for our device and the results are confirmed using full-wave simulations. The error incurred by not using this method and employing a reference sample for calibration or by using saturation magnetization “Ms” and anisotropy field “Ha” is shown to be anywhere between 5% and 40% and possibly even more. Our measurement set up is capable of measuring films as thin as 300 nm with a relative permeability as low as 10.

High frequency magnetic properties of ferromagnetic thin films and magnetization dynamics of coherent precession

“…[156][157][158][159][160][161][162][163][164] In order to obtain the permeability spectrum of thin film (PSTF), it was suggested that a wideband measurement can reveal the frequency dependence of permeability. [165][166][167][168][169][170][171] After that, the measurement of the PSTF has been developed both in design [172,173] and in static magnetic field modulation. [174,175] More recently, the electric detection of FMR based on the spin rectification effect (SRE) was suggested, by which the dynamics of magnetization has been observed even at large cone angle.…”

“…Recently, Sebastian develop an improved-accuracy thin film permeability extraction for a microstrip permeameter, in which the following issues faced in the conventional permeability extraction methods are overcome: [173] (i) the need of a known reference sample, (ii) the need for an external dc magnetic field biasing/saturation source, (iii) a priori knowledge of saturation magnetization M s and anisotropy field H K , which are extremely difficult and error-prone to measure, (iv) the use of brute force complex optimization or simplified conformal mapping techniques. It is shown using full-wave simulations that several of the conventional assumptions made for extracting permeability data from a microstrip permeameter are not justified.…”

Magnetic domain structure in nanocrystalline Ni-Zn-Co spinel ferrite thin films using off-axis electron holography

“…The real l 0 and imaginary l 00 permeabilities were measured as a function of frequency using a vector network analyzer with a customized microstrip permeameter. 8 For cross-section TEM and off-axis electron holography characterization, samples were prepared using cutting, mechanical polishing, followed by dimpling to create thin areas with total thicknesses of about 10 lm. Samples in the plan-view geometry were also prepared, with dimpling and ion-milling done only from the back side of the wafer.…”