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Controls of spin dependent tunneling in 2-dimensional granular magnetic films and development of active devices

二维颗粒磁性薄膜中自旋相关隧道的控制和有源器件的开发

基本信息

批准号：
12650314
负责人：
HONDA Shigeo
金额：
$ 2.37万
依托单位：
Shimane University
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 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650314/
关键词：
granular films low dimensional array tunneling magnetoresistance extraordinary Hall effect ferromagnetic semiconductor Coulomb blockade porous Si ion implantation 2次元分散型 Fe-SiO_2 Co-SiO_2 Co-Bi tトンネル磁気抵抗効果 CEMS トンネル効果磁気抵抗効果

项目摘要

1. Film thickness dependence of magnetization and magnetoresistance in Fe-SiO2 granular films.The saturation magnetization increases with thickness, and a step behavior appears at around 200 nm in the thickness dependence of the magnetization and transport properties. These behaviors are explained by a model of double-layered structure; the first layer near the substrate having smaller magnetization and the second layer with larger magnetization. These magnetic and transport properties is explained by a model, in which the formation of non-magnetic shell is enhanced near the substrates. These structure was confirmed by X-ray photoelectron spectroscopy.2. Tunneling magnetoresistance in low-dimensional Co-SiO2 films.(1) The tunneling giant magnetoresistance properties have been examined for ultrathin Co-SiO_2 granular films, forming the pseudo 2-dimensional alignment of Co granules. In the 35 vol.%-Co films of 5 and 10 nm thickness, the magnetoresistance (MR) ratio increased with reducin … More g temperature similar to thick films. On the other hand, in the 28 and 32 vol.%-Co films thinner than 5 nm, the MR ratio decreased drastically below 100K with reducing temperature reflecting the 2-dimensional alignment of Co granules.(2) Samples of CPP (current perpendicular to plane) structure with narrow current pin-holes, AuCr/SiO_2/Co-SiO_2/SiO_2/AuCr, exhibited the non-linearity in current to voltage (I-V) relation, suggesting that the tunneling barrier tunneling probabilities of majority or minority spin band relating to the variation of E.3. Magnetic and transport properties of alternately deposited Co-Bi films.Both ordinary magnetoresistance (OMR) and anisotropic magnetoresistance (AMR) are observed in Co-Bi films. The OMR component, for which the Bi matrix is responsible, decreases with increasing Co volume fraction x, while the AMR component, due to Co, increases. For x = 17, the spontaneous Hall resistivity indicates strong temperature dependence. With the increase of temperature, polarity switches at 150 K from negative to positive. At room temperature Hall Resistivity or Hall coefficient shows a larger value than pure Co bulk by 2 orders of magnitude.4. Extraordinary Hall effect in Co implanted GaAs hybrid magnetic semiconductors.Hybrid Co/GaAs ferromagnetic semiconductors have been prepared by implantation method. In these samples, sheet resistance shows weak temperature dependence, and the extraordinary Hall effect with positive coefficient is observed. In small Co content samples, Hall resistance increases with decreasing temperature and maximum value of 3.6 x 10-2 Ω is obtained at 150 K. Less

1. Fe-SiO2颗粒膜的磁化强度和磁电阻随膜厚的变化，饱和磁化强度随厚度的增加而增加，磁化强度和输运性质随厚度的变化在200 nm附近出现台阶。这些行为是由一个双层结构的模型来解释的;靠近衬底的第一层具有较小的磁化强度，第二层具有较大的磁化强度。这些磁性和输运性质解释了一个模型，在该模型中，非磁性壳层的形成增强附近的基板。通过X射线光电子能谱证实了这些结构.低维Co-SiO2薄膜的超导磁电阻(1)研究了Co-SiO_2颗粒膜的隧穿巨磁电阻特性，形成了Co颗粒的赝二维排列。在35 vol. %-在5和10 nm厚度的Co薄膜中，随着薄膜厚度的减小， ...更多信息 g温度类似于厚膜。另一方面，在28和32体积%-当Co薄膜厚度小于5 nm时，随着温度的降低，薄膜的磁电阻率在100 K以下急剧下降，这反映了Co颗粒的二维取向。(2)具有窄电流针孔的CPP结构样品AuCr/SiO_2/Co-SiO_2/SiO_2/AuCr在电流-电压（I-V）关系中表现出非线性，表明隧穿势垒隧穿几率与E.3的变化有关. Co-Bi交替沉积薄膜的磁性和输运性质Co-Bi薄膜中既有普通磁电阻（OMR），也有各向异性磁电阻（AMR）。的OMR组件，其中的Bi矩阵负责，随着Co体积分数x的增加而减少，而AMR组件，由于Co，增加。对于x = 17，自发霍尔电阻率表明强烈的温度依赖性。随着温度的升高，在150 K时，极性由负向正转变.在室温下，其霍尔电阻率或霍尔系数比纯Co体电阻大2个数量级. Co注入GaAs混合磁性半导体中的异常霍尔效应用离子注入法制备了Co/GaAs混合铁磁半导体。在这些样品中，薄层电阻表现出弱的温度依赖性，并观察到具有正系数的异常霍尔效应。在Co含量较少的样品中，霍尔电阻随温度的降低而增大，在150 K时达到最大值3.6 × 10 ~（-2）Ω。少