High Frequency Soft Magnetic Performance on Magnetically Isotropic Co-Al-N Films in External Bias Field

Abstract

We have investigated the high frequency soft magnetic properties ( -properties) of magnetically isotropic Co Al N films with an external bias field applied in various directions. The films are prepared by sputtering and consist of fine Co grains 5 nm in diameter in an amorphous AlN matrix. The films have relatively large magnetic anisotropy perpendicular to the film plane and are magnetically soft. The initial magnetization curve in the film plane varies slightly with changes in the direction of the magnetizing field. A clear peak of permeability was found at a resonance frequency around 2.5 GHz when the film had been magnetically saturated normal to the -field in the film plane before measurement. After being magnetically saturated parallel to , the film shows a broad peak in around 9 GHz; however decreases to 2.5 GHz with increasing normal to the film plane. Control of between 2.5-9.65 GHz was achieved by changing the direction of , which is attributed to the direction changes in magnetic moments of a magnetically isotropic film.Index Terms-High frequency, nitride film, resonance frequency, soft magnetic property.

Permeability Measurement up to 30 GHz of a Magnetically Isotropic Thin Film Using a Short-Circuited Coaxial Line

“…The rated frequency of APC-7 is 18GHz, which relates to the cutoff frequency fc of TE11 mode as a higher harmonic and is given as follows 12) : fc = (c /2){2/(a + b)} (6) where, c is the speed of light, and a and b are the inner and outer diameters, respectively, of the coaxial line.…”

“…Amorphous Co-Zr-Nb films and Fe-Ni films with uniaxial anisotropy are typical magnetic thin films exhibiting high permeability at high frequencies, but their natural resonant frequencies are limited to few-gigahertz bands. In our group, nanogranular films with a higher natural resonant frequency were prepared by sputtering 5,6,7,8) .…”

(Co–Ti–O)/Bi–Ti–O Multilayer Films with High-Frequency Electromagnetic Response

“…11) The key concept of this study originates from the excellent high-frequency soft-magnetic properties realized in recent nanogranular thin films. The heterogeneous nanogranular structure consisting of multiple combinations of magnetic nanograins and an insulator matrix (e.g., Co-AlN, [12][13][14] Co-TiN, 15) and Fe-Al 2 O 3 16) ) enables the films to exhibit a large at frequencies of up to a few GHz. The size and density of magnetic nanograins (or the insulator matrix) are essential parameters, because they strongly affect both and " [i.e., ferromagnetic coupling among the magnetic grains, electrical resistivity (), percolation threshold, and saturation magnetization (B s )].…”

Control of the static and high-frequency magnetic properties of perpendicular anisotropic Co–HfN granular films through insertion of HfN interlayers

“…Several subsequent studies later demonstrated the occurrence of PMA in Co-Zr-O 7) and Co-Al-O films. 9,10) Recently, Kijima et al 11,12) have reported another kind of PMA in Co-Al-N granular films due to the presence of a small fraction of perpendicular components and found that the films exhibit in-plane isotropic high-frequency response of permeability, in which the columnar granules most likely served as the origin of the perpendicular magnetic components. Subsequently, we observed the stripe domains with rotational magnetic anisotropy from the surface of Co-Hf-N films, 13) suggesting that they could potentially be used as the magnetic core for inductors regardless of their orientation.…”

“…Thus, changing the perpendicular magnetization over the separation of columnar grains should be possible. In this work, we have successfully controlled the transition between magnetic softness (defined by the coercivity H c < 20 Oe and the remnant magnetization ratio M r =M s of ∼1) and PMA (a small fraction of perpendicular components as observed in Co-Al-N 11,12) and Co-Hf-N 13) granular films), and changed the high-frequency band f r from 2 to 0.9 GHz by carefully tuning the thickness of Co-HfN granular layers and HfN interlayers.…”