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

为了开发用于电感、滤波器和传输线器件等各种微波无源器件的新型高频磁性薄膜材料，提出了一种铁氧体/反铁氧体交换耦合材料。在本研究中，我们制备了一种Mn-Ir/Fe-Si交换耦合薄膜，并对其进行了表征。取得的结果如下：1.研究结果。铁/反铁交换耦合对新型高频磁性材料的敏感性众所周知，铁/反铁交换耦合在铁磁层中产生交换偏置磁场。本研究提出了一种利用铁氧体/反铁氧体交换耦合来开发高频磁性材料的新思路。Mn-Ir/Fe-Si交换耦合膜的制备与表征(1)铁磁共振频率的控制研究发现，可以通过改变铁磁层厚度来控制铁磁共振频率。例如，在Mn-Ir(10 Nm)/Fe-Si薄膜中，铁磁共振频率变化…(2)Ru底层对Mn-Ir/Fe-Si薄膜磁性能的影响：底部Fe-Si超薄(1 Nm)Ru底层具有很大的矫顽力，抑制磁各向异性色散，并通过改善薄膜的表面粗糙度来缩小FMR谱线宽度。通过引入Ru底层，可以制备出谐振损耗较小的高频磁性材料。(3)宽带吸能磁性材料；不同Fe-Si层厚度的Mn-Ir/Fe-Si多层膜具有多个磁阻抗，适合作为宽带吸声材料。(4)微波磁性能分析；为了研究Mn-Ir/Fe-Si薄膜的微波磁性能，基于Landau-Lifshitz-Gilbert方程，将Fe-Si的交换刚度色散模型引入微磁模拟。认为这种交换刚性是由于Fe-Si晶体取向和晶格缺陷所致。Fe-Si中的交换刚度色散导致自旋-自旋相互作用的损失，而交换偏置磁场的色散导致铁磁层较厚时产生较宽的FMR线宽。为了开发窄线宽铁磁共振材料，在铁氧体/反铁氧体交换耦合薄膜中引入更薄的铁磁层是非常有效的。(5)铁氧体/反铁氧体交换耦合膜在微波器件中的应用问题；为了阐明铁氧体/反铁氧体交换耦合膜在微波器件中的应用问题，研究了热应力对器件制作过程的影响。虽然Mn-Ir/Fe-Si界面的交换能随温度的升高而单调下降，但即使在300℃时也下降了约30%。因此，认为通过器件工艺对性能的热退化不是那么严重。未来的问题(1)利用铁氧体/反铁氧体交换耦合膜的微波无源材料的发展；新型铁氧体/反铁氧体交换耦合膜将应用于电感、滤波器和传输线器件等微波无源器件。(2)其他用于微波应用的新型铁氧体/反铁氧体交换耦合膜的研究；作为其他新型铁氧体/反铁氧体交换耦合膜材料，金属氧化物多层体系材料和金属氧化物纳米颗粒体系材料将被制备并表征。我们目前正在研究一种纳米颗粒铁氧体/反铁氧体交换耦合薄膜。较少

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