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

磁性颗粒复合薄膜是由纳米级的铁磁金属颗粒（如Co）分散在绝缘体基体（如Sm_2O_3）中而成的，由于其具有额外的自由度（e. G.颗粒尺寸和金属体积分数）使我们能够为应用制造定制的介质。特别是，这些薄膜所表现出的大的隧道型磁阻（TMR）效应对于构建用于各种电子应用的磁头和传感器是有用的;薄膜的软磁TMR效应变得不可或缺。本文采用磁控溅射法制备了Co-Sm-0薄膜，用FeNi倾斜溅射法制备了Co-Sm-0薄膜，并在此基础上制备了Co-Sm-0薄膜。将衬底放置在固定到阴极的倾斜角θ= 60度的铜楔上。铁磁薄膜 关于我们 (Fe采用<20><80>射频磁控溅射技术，在倾斜阴极布置下制备了具有纳米尺度结构的（Co，Ni和Fe_ Ni_）薄膜。斜向溅射可以有效地形成自组织的纳米尺度的纳米结构，其平均高度和间距约为10 nm。由于形状效应，所得到的膜清楚地表现出单轴面内磁各向异性，但易轴的大小和方向从样品到样品的变化强烈地取决于材料和膜厚度（沉积时间）。除了形状效应外，晶体磁各向异性对纳米尺度磁结构单轴各向异性的形成也起着重要作用。在此基础上，采用Co_<76>（Sm_2O_3）_<24>（f_v= 52 vol.%）在平均厚度为20 nm的FeNi倾斜溅射沉积膜上直接沉积厚度为43 nm的颗粒膜。由于相邻的FeNi纳米尺度微结构之间的间隙中的杂散场，复合膜表现出相当软的磁化强度。薄膜的磁软化改善了薄膜的低场TMR响应：在500 e的小场下，薄膜的Δp/p0（p0 = 2.9 × 10^5 μΩcm）值达到3%以上。由此计算出复合膜的场灵敏度Δp/p0约为Co-Sm-0单层膜的240倍，表明了倾斜溅射FeNi底层膜的有效性。少

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