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Developmental Research of Ferromagnetic Thin Films for Surface Acoustic Wave with Field-Induced Giant Attenuation

场致巨衰减声表面波铁磁薄膜的研究进展

基本信息

批准号：
62850130
负责人：
FUJIMORI Hiroyasu
金额：
$ 3.9万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-62850130/
关键词：
Surface Acoustic Wave Field-induced attenuation effect in SAW device SAW device Sputtered multi-layered thin film Ferromagnetic amorphous thin film ac magnetic susceptibility hysteresis loop Coercive force スパッター法金属膜作製交流帯確率多層確性膜

项目摘要

SAW delay line with evaporated nickel films shows an attenuation peak in a magnetic field parallel to the film plane which strongly depends on film thickness and magnetic fields. The maximum attenuation induced by fields was found to become about 40 dB/cm at 20 Oe (= H_c) for 200 A^^ﾟ thick Ni film. In order to get a SAW device having much larger attenuation effect, we have prepared the SAW devices with multi-layered Ni/W films. It was found that the field-induced attenuation was enhanced in proportion to the number of Ni layers. These results indicate that a SAW device with multi-layered Ni/W films gives a very large attenuation which can not be obtained with the single layered Ni film.In this term of project(1989), we firstly tried to get the SAW device which can control the attenuation by a small bias magnetic field. We have prepared amorphous thin films of (Fe_<1-x>Co_x)_<85>Zr_<15> on the substrates of Foto-ceram and quartz by ac plasma sputtering and studied the hysteresis loop and the field dependence of ac susceptibility. When the amorphous films are made by sputtering under an argon gas atmosphere with pressure less than 1 X 10^<-3> Torr, the films were found to have coercive force less than 1 Oe, at which the ac susceptibility shows a very large peak compared with that of a single layered Ni film. Then we have got one of the most suitable films for the SAW device which will show very large field-induced attenuation by a small magnetic field.Secondly, we designed the new SAW device made of lithium tantalate (LiTaO_3) with larger electromechanical coupling factor than that of crystalline quartz. We prepared the four kinds of SAW devices of 10 mm x 5 mm dimension which can generate SAW of 200, 500, 700 and 900 MHz,' respectively (the SAW devices were offered by the good offices of FUJITSU LIMITED). Testings of the above SAW devices with amorphous (Fe_<1-x>Co_x)_<85>Zr_<15> films are now in progress.

蒸发镍薄膜的SAW延迟线在平行于薄膜平面的磁场中出现衰减峰，衰减峰与薄膜厚度和磁场有很大关系。对于200 A^^厚的Ni薄膜，在20 Oe （= H_c）时，电场诱导的最大衰减约为40 dB/cm。为了得到衰减效果更大的声表面波器件，我们制备了多层Ni/W薄膜的声表面波器件。结果表明，场致衰减随Ni层数的增加而增大。这些结果表明，采用多层Ni/W薄膜的SAW器件具有单层Ni薄膜所不能达到的非常大的衰减。在本项目（1989年）中，我们首先尝试了用一个小的偏置磁场来控制衰减的SAW器件。采用交流等离子溅射的方法在Foto-ceram和石英衬底上制备了（Fe_<1-x>Co_x）_<85>Zr_<15>的非晶薄膜，并研究了其磁滞回线和交流磁化率的场依赖性。在压力小于1 × 10^<-3> Torr的氩气气氛下溅射制备非晶薄膜时，发现薄膜的矫顽力小于1 Oe，与单层Ni薄膜相比，其交流磁化率峰值非常大。然后我们得到了一种最适合用于声表面波器件的薄膜，它可以在很小的磁场下表现出非常大的场致衰减。其次，设计了机电耦合系数大于晶体石英的钽酸锂（LiTaO_3） SAW器件。我们制备了4种尺寸为10 mm × 5 mm的声表面波器件，分别能产生200mhz、500mhz、700mhz和900mhz的声表面波（声表面波器件由富士通有限公司提供）。上述SAW器件的非晶（Fe_<1-x>Co_x）_<85>Zr_<15>薄膜的测试目前正在进行中。