Study on ferro/anti-ferro exchange-coupled multilayer film for microwave magnetic devices

点击翻译按钮获取中文摘要

In order to develop a new high frequency magnetic film material for various microwave passives such as inductor, filter and transmission-line device, a ferro/anti-ferro exchange-coupling been introduced. In this study, a Mn-Ir/Fe-Si exchange-coupled film has been fabricated and characterized. The results obtained are as follows.1. Apossibility of new high frequency magnetic material by means of ferro/anti-ferro exchange-couplingAs well-known, ferro/anti-ferro exchange coupling generates exchange bias magnetic field in the ferromagnetic layer. In this study, a new idea which high frequency magnetic material can be developed using ferro/anti-ferro exchange coupling has been proposed.2. Fabrication and characterization of Mn-Ir/Fe-Si exchange-coupled film(1) Control of ferromagnetic resonance frequency ; It was found that the ferromagnetic resonance (FMR) frequency can be controlled by changing ferromagnetic layer thickness. For example, in Mn-Ir(10nm)/Fe-Si film, the FMR frequency varies … More 1.9 from 4.3 GHz by changing Fe-Si layer thickness of 100 from 10nm.(2) Effect of Ru under-layer on the magnetic properties of Mn-Ir/Fe-Si film ; Ultra thin (1nm) Ru under-layer for bottom Fe-Si has a great effect of coercive force, suppression of magnetic anisotropy dispersion, and narrow FMR line width by improving surface roughness for the film. By introducing Ru under-layer, high frequency magnetic material with small resonance loss can be fabricated.(3) Wideband energy absorption magnetic material ; Mn-Ir/Fe-Si multilayer film with different Fe-Si layer thickness has plural FMRs and is suitable for wideband noise absorption material.(4) Analysis of microwave magnetic property ; In order to investigate microwave magnetic property of the Mn-Ir/Fe-Si film, exchange stiffness dispersion model for the Fe-Si has been introduced to the micromagnetic simulation based on the Landau-Lifshitz-Gilbert equation. It has been assumed such exchange stiffness is owing to the Fe-Si grain orientation and lattice defect. The exchange stiffness dispersion in Fe-Si gives rise to lose spin-spin interaction, and dispersion of exchange bias magnetic filed gives rise to wide FMR line width in case of thick ferromagnetic layer. In order to develop narrow FMR line width material, it is very effective to introduce thinner ferromagnetic layer to the ferro/anti-ferro exchange coupled film.(5) Problem in the application of ferro/anti-ferro exchange-coupled film to microwave devices ; In order to clarify the problem in the application of ferro/anti-ferro exchange-coupled film to microwave devices, influence of the thermal stress in the device fabrication process has been investigated. Although the exchange energy in Mn-Ir/Fe-Si interface decreases monotonously with increasing temperature, its decrease is about 30% even when 300℃. Hence it is considered that the thermal degradation of the property through the device process is not so serious.3. Future issues(1) Development of microwave passives using ferro/anti-ferro exchange-coupled film ; A new ferro/anti-ferro exchange-coupled film will be applied to the microwave passives such as inductor, filter and transmission-line device.(2) Investigation of other new ferro/anti-ferro exchange-coupled film for microwave application ; As other new ferro/anti-ferro exchange-coupled film material, metal-oxide multilayer system material and metal-oxide nano-granular system material will be fabricated and characterized. We currently investigate a nano-granular ferro/anti-ferro exchange coupled film. Less