Dynamical magnetic behavior of anisotropic spinel-structured ferrite for GHz technologies

Abstract

We have fabricated a high quality magnetic Ni0.5Zn0.5Fe2O4 ferrite powder/polymer composite sheet consisting of common and environmentally friendly elements only. The sheet was then tested for its dynamic permeability by irradiating with electromagnetic waves with frequencies up to 50 GHz. Two different originally developed methods were used for the high-frequency permeability measurements, a short-circuited microstrip line method and a microstrip line-probe method. It is challenging to measure the dynamic permeability of magnetic thin films/sheets beyond 10 GHz because of the low response signal from these materials. However, the two methods produced essentially equivalent results. In the frequency dependent permeability profile, the maximum position of the profile, $$\mu ^{\prime \prime }_{max}$$ μ max ″ , shifted towards higher frequencies upon increasing an applied (strong) static external magnetic field, $$H_{dc}$$ H dc . A linear relationship between $$\mu^ {\prime \prime }_{max}$$ μ max ″ and $$H_{dc}$$ H dc for the entire range of $$H_{dc}$$ H dc was observed even at small $$H_{dc}$$ H dc . In general, the spinel-structured Ni-based ferrites exhibit low magnetic anisotropy, but the present sample showed a uniaxial-anisotropic behavior in the parallel direction of the sheet. Our Ni0.5Zn0.5Fe2O4 powder/polymer composite sheet thus exhibits high performance at GHz frequencies, and should be applicable e.g. as an anisotropic electromagnetic wave-interference material.

Bonding microwave absorbing ferrites to thermal conducting copper

“…Within the microwave frequency, the relaxation is mainly contributed by spin rotation, or electron hopping between Fe 2+ /Fe 3+ or between other transition metallic ions. [8][9][10] The absorbing ability can be tailored through the change of specimen thickness. 9 The shielding effectiveness of NiZn-ferrite and MgZn-ferrite is better than that of MnZn-ferrite.…”

“…Ferrites exhibit high saturated magnetization, high electrical resistance and superb chemical stability. [6][7][8] They are gaining their importance in the area of high-frequency devices, such as circulator, isolator, phase shifter, and antennas etc. 7 The absorbing capability of ferrites can be related to domain wall motion resonance and spin rotational relaxation.…”

“…7 The absorbing capability of ferrites can be related to domain wall motion resonance and spin rotational relaxation. [6][7][8][9] The domain wall motion is strongly affected by the microstructure (grain size and porosity), the spin rotation by density. 7 With the increase of frequency, the spin rotation gains more influence on relaxation.…”

New characteristic parameter of energy loss in permalloy

“…It can be seen that the last one of metallic SMMs is the most promising mechanism to realize excellent performance in the MHz range [24]. Experimental cut-off frequency determined by domain wall replacement and nature resonance can not be observed in susceptibility spectra of metallic SMMs [25], but in that of ferrite [26][27][28]. Apparently, 100 kHz cut-off frequency is not completely determined by above mechanisms.…”

Resonance frequency above 20 GHz in superparamagnetic NiZn-ferrite

“…Polycrystalline nickel-zinc ferrite (NZF) thin films prepared by the spin-spray method show excellent high-frequency magnetic characteristics with high permeability (>50) and natural resonance as high as 3 GHz. 19,20 However, the particle size is in the range of 100-300 nm, and thus, is not superparamagnetic. It will be fascinating to see if Snoek's limit on superparamagnetic NZF thin films can be broken, allowing for applications in high frequency devices, especially in the mm-wave range relevant to 5G technologies.…”