Noise analysis of a 1 MHz–3 GHz magnetic thin film permeance meter

Abstract

We analyzed the permeability measurement error of a low permeance thin film. We clarified that the noise voltage was excited by a current loop which is composed of the coaxial cable and the ground plane. The current loop should be removed for high sensitivity of the permeameter. The permeability of a high electrical resistivity film (CoFeHfO) has been demonstrated 1 MHz–3.5 GHz.

Microstructures and Soft Magnetic Properties of High Saturation Magnetization Fe-Co-N alloy Thin Films

“…The hard-axis magnetic permeability was measured by a custom-built permeameter with a frequency range up to 3 GHz on samples with an area of 5 × 5 mm 2 . The details of the permeameter are available in reference [11]. The resistivities of these FeCoN films were measured with a four-point probe station.…”

Novel nanostructure and magnetic properties of Co–Fe–Hf–O films

“…It was shown that the structure of a Co-Fe-Hf-O film consisted of α-Fe(Co)-rich bcc nanograins embedded in a HfO 2 -rich amorphous matrix [10,17,19]. The highly resistive HfO 2 -rich amorphous matrix contributed to the high resistivity of the film which significantly suppressed eddy current loss, and consequently gave rise to the good highfrequency performance [10][11][12][13][14][15][16][17]. The addition of large amounts of Hf and O was found to significantly increase the electrical resistivity of Co-Fe-Hf-O films but, in turn, deteriorate their magnetic softness [17,18].…”

“…Hayakawa et al [10] first reported that Fe-M-O (M = Hf, Zr) magnetic films possessed a good magnetic softness owing to their nanostructure which consisted of ferromagnetic bcc nanocrystals (∼10 nm in size) embedded in an amorphous matrix containing large amounts of M and O elements. Soon after this work, several attempts were made to improve the high-frequency performance of these films [11][12][13][14][15][16][17][18][19]. It was found that the addition of Co to Fe-Hf-O films led to a significant improvement in the high-frequency magnetic response, mainly due to an increase in the crystalline anisotropy of the nanograins.…”

“…In this context, the recent findings of new magnetic oxide thin films are of practical importance in high-frequency applications because these materials can show a good highfrequency performance into the gigahertz range owing to their resistivity, which is approximately ten times higher than that of conventional magnetic alloy films [6,7,[10][11][12][13][14][15][16][17][18][19]. Hayakawa et al [10] first reported that Fe-M-O (M = Hf, Zr) magnetic films possessed a good magnetic softness owing to their nanostructure which consisted of ferromagnetic bcc nanocrystals (∼10 nm in size) embedded in an amorphous matrix containing large amounts of M and O elements.…”

“…Recently there has been an emerging demand for the use of magnetic thin films in high-frequency applications including magnetic recording write-heads and soft underlayers for perpendicular media and thin film wireless inductor cores [6,7,[10][11][12][13][14][15][16][17][18][19]. For these applications, magnetic thin films are required to have high electrical resistivity (ρ) to minimize energy loss due to eddy currents, and a large saturation magnetization (4π M s ) and hard-axis anisotropy field (H kH ) to increase the magnetic switching capacity at high frequencies [7,10].…”