Self assembled nanoscale structure - super sensitive tunneling magnetoresisitance effect of dielectric and ferromagnetic hybrid structure

自组装纳米结构——介电铁磁混合结构的超灵敏隧道磁阻效应

基本信息

批准号：
12650311
负责人：
INOUE Mitsuteru
金额：
$ 2.62万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Granular magnetic composite films, in which nano-scale ferromagnetic metal particles such as Co are dispersed in insulator matrices such as Sm_20_3, are attractive materials for electronic applications, because the extra degrees of freedom (e. g. granule size and metal volume fraction) of films enable us to fabricate tailored media for applications. Especially, the large tunneling-type magnetoresistance (TMR) effect that these films exhibit is useful for constructing magnetic heads and sensors for various electronic applications ; magnetically soft TMR effect of films becomes indispensable. In this report, we demonstrate that the low field response of the resistivity change of Co-Sm-0 films can be improved considerably by employing FeNi obliquely sputtered films as the underlayer of the granular films.Films were prepared by using a rf-magnetron sputtering apparatus. The substrate was placed on a copper wedge with inclination angle θ=60deg fixed to the cathode. Ferromagnetic thin films … More (Fe, Co, Ni and Fe_<20>Ni_<80>) with nano-scale structures were formed by RF magnetron sputtering under oblique cathode arrangements. The oblique sputtering was effective to form self-organizing like nano-scale corrugate structures whose average height and spacing were approximately 10 nm. The resultant films clearly exhibited uniaxial inplane magnetic anisotropy due to the shape effect, but the magnitude and the direction of easy axis changed from sample to sample depending strongly on the material and the film thickness (deposition time). Beside the shape effect, crystalline magnetic anisotropy also plays an important role for the formation of uniaxial anisotropy of the nano-scale magnetic structures.An underlayer of composted film used an obliquely sputtered FeNi films were subject to post ion-milling etching. Then, The Co_<76>(Sm_20_3)_<24> (f_v=52vol.%) granular film with 43 nm thickness was directly deposited onto the FeNi obliquely sputter deposited film with the average thickness of 20 nm. The composite film exhibited a considerably soft magnetization due to the stray field in gaps between neighboring FeNi nano-scale corrugate structures. The magnetic softening of film yielded the improvement of low field TMR response : with a small field of 500e, the Δp/p_0(p_0=2.9X10^5μΩcm) value of film reached more than 3 %. From this value, the field sensitivity of Δp/p_o of the composite film is evaluated to be about 240 times higher than that of the Co-Sm-0 single-layer film, suggesting the effectiveness of the obliquely sputtered FeNi underlayer film. Less

颗粒磁性复合薄膜，其中纳米级铁磁金属颗粒（如 Co）分散在绝缘体基体（如 Sm_20_3）中，对于电子应用来说是有吸引力的材料，因为薄膜的额外自由度（例如颗粒尺寸和金属体积分数）使得特别是，这些薄膜表现出的大隧道型磁阻（TMR）效应对于构建各种电子应用的磁头和传感器非常有用；薄膜的软磁TMR效应变得不可或缺。在本报告中，我们证明，通过采用FeNi倾斜溅射薄膜作为颗粒薄膜的底层，可以显着改善Co-Sm-0薄膜电阻率变化的低场响应。通过使用放置射频磁控管的溅射装置来制备基板在固定至铁磁体的倾斜角θ=60°的铜楔上。在倾斜阴极薄膜排列下，通过射频磁控溅射形成了具有纳米级结构的薄…更多（Fe、Co、Ni和Fe_<20>Ni_<80>）。倾斜溅射可以有效地形成纳米级的自组织结构。由于形状效应，平均高度和间距约为10 nm的波纹结构明显表现出单轴面内磁各向异性，但易磁化轴的大小和方向随样品而变化。样品强烈依赖于材料和薄膜厚度（沉积时间），除了形状效应外，晶体磁各向异性对于纳米级磁性结构的单轴各向异性的形成也起着重要作用。复合薄膜的底层采用倾斜的方式。然后，对溅射的FeNi薄膜进行后离子铣削蚀刻，得到Co_ 76 (Sm_20_3)_ 24 (f_v＝52vol.％)。将厚度为 43 nm 的颗粒薄膜直接沉积在平均厚度为 20 nm 的 FeNi 倾斜溅射沉积薄膜上，由于相邻 FeNi 纳米级波纹结构之间的间隙中存在杂散场，该复合薄膜表现出相当软的磁化。薄膜的软化改善了低场 TMR 响应：在 500e 的小场下，薄膜的Δp/p_0(p_0=2.9X10^5μΩcm)值达到3%以上，由此评价复合薄膜的Δp/p_o场灵敏度比Co-Sm高约240倍。 -0单层薄膜，表明倾斜溅射FeNi底层薄膜的有效性较低。