High frequency characteristics of NiO/(FeCo/NiO)10 multilayers with exchange anisotropy

Flexible tuning microwave permeability spectrum in [ferromagnet/antiferromagnet]nexchange-biased multilayer stack structure

“…Different exchange bias fields H ex1 = 0.9 mT, H ex2 = 2.6 mT, and H ex3 = 7.1 mT are identified from this three-stage hysteresis loop. Since the static effective anisotropy field can be obtained as H stat keff = H ex +H ua , [13,14] where H ua is the uniaxial anisotropy field, in principle, one can easily tune the effective anisotropy field as well as the resonance frequency by changing the thickness of FM layer in both partially pinned FM layer and [AF/FM/AF] n stack structure. Therefore, tunable resonance linewidth can be realized by overlapping the adjacent resonance frequencies.…”

“…The discrepancy in [IrMn(15 nm)/NiFe(30 nm)/IrMn(15 nm)] 4 with a small NiFe thickness is up to 6.3 mT, which is much larger than the discrepancy in [IrMn(15 nm)/NiFe(40 nm)/IrMn(15 nm)] 5 . A reasonable hypothesis to explain such a phenomenon is that the dynamic effective anisotropy of the ferromagnetic layer in FM/AF exchange bias system is composed of uniaxial anisotropy, unidirectional exchange bias, and angleindependent rotatable anisotropy, [13,21] where the rotatable anisotropy depends inversely on the FM film thickness. [21] Consequently, by overlapping the four FMR frequencies with different values of H dyn keff , an ultra-wide resonance linewidth imaginary permeability spectrum with a 3.1-GHz linewidth (0.6 GHz to 3.7 GHz) is experimentally achieved which is very beneficial for wideband microwave noise suppression.…”

Высокочастотная магнитная проницаемость однослойных и многослойных нанокомпозитов (Co-=SUB=-41-=/SUB=-Fe-=SUB=-39-=/SUB=-B-=SUB=-20-=/SUB=-)-=SUB=-x-=/SUB=-(SiO-=SUB=-2-=/SUB=-)-=SUB=-100-x-=/SUB=-

“…Для подавления этих эффектов в литературе предложено несколько способов, а именно напыление многослойных структур из чередующихся слоев металла и диэлектрика или создание обменной анизотропии [10,11]. Однако введение немагнитных слоев диэлектрика уменьшает намагниченность насыщения, а использование разных материалов в мультислоях усложняет технологию.…”

Effect of multilayer structure on high-frequency properties of FeCo/(FeCo)0.63(SiO2)0.37 nanogranular films on flexible substrates

“…For the monolayer ferromagnetic films, it is promising to achieve high microwave permeability to increase film thickness. However, the negative influence, the serious skin effect and eddy current [4,5], and the obvious out-of-plane anisotropy in the high frequency, will block the increasing of the permeability, while the thin magnetic films, with specific multilayer structure design, can efficiently avoid the above negative effect and improve high-frequency properties by leading into different dielectric layers [6]. In this study, FeCo-SiO 2 monolayer films and FeCo/(FeCo) 0.63 (SiO 2 ) 0.37 multilayer films were prepared by co-sputtering and tandem sputtering on flexible substrates, respectively, and in order to discuss the improvement of multilayer films, the high-frequency properties of both films whose FeCo content was about 72 at % were investigated.…”