Spin transistor using tunneling barrier

使用隧道势垒的自旋晶体管

基本信息

批准号：
14205056
负责人：
IWATA Satoshi
金额：
$ 31.2万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14205056/
关键词：
Magnetic random access memory Spin tunneling effect Spin dependent conduction Nano magnet Exchange Anisotropy Antiferromagnet Thermomagnetic writing Amorphous alloy 磁気固体メモリ反強磁性膜ナノ構造ブロッキング温度

项目摘要

Spin tunneling devices were fabricated by the magnetron sputtering system with 5 targets, where the metal masks for forming the electrodes were changed in vacuum system. Magnetoresistance(MR) ratio increased from few % to over 20% and the reproductivity of tunneling junction was improved by changing the magnetic layers from polycrystalline NiFe to amorphous CoFeB layer. This is due to improvement of the flatness of interface because of the structure without polycrystalline grains. Oxidization process of Al layer were investigated by dc plasma and rf plasma discharge in pure oxygen. In case of dc plasma, the tunneling devices exhibit large MR ratio with spin valve type MR curves in the range of the Al thickness between 1.3 nm and 1.6 nm and MR ratio shows maximum value of 30% at 1.4 nm. The dispersion of MR ratio between seven samples prepared at same process becomes very small. In case of rf plasma, although the MR ratio is 15% at Al thickness of 1.6nm, it decreases with decreasing Al thickness and becomes less than 1% at 1.3 nm. The dispersion of MR ratio between samples is larger than that for dc plasma case. These results show that the dc plasma is more suitable for oxidization of Al layer compared with rf plasma. However, the MR ratio for dc plasma case decreases more steeply with increasing voltage bias compared with rf plasma case, which implies that the oxidization process by dc plasma also should be improved. It is considered that these results are due to the deference in the degree of oxidization of Al layer and interface roughness of tunneling barrier. The tunneling devises show good thermal stability, where MR ratio does not change below 300 C annealing in the vacuum.

自旋隧道器件是通过具有5个靶材的磁控溅射系统制造的，其中用于形成电极的金属掩模在真空系统中改变。通过将磁性层从多晶NiFe改为非晶CoFeB层，磁阻（MR）比从百分之几增加到20%以上，并且隧道结的再现性得到改善。这是由于由于没有多晶晶粒的结构而提高了界面的平坦度。采用纯氧中直流等离子体和射频等离子体放电研究了Al层的氧化过程。在直流等离子体的情况下，隧道器件在Al厚度在1.3 nm和1.6 nm之间的范围内表现出具有自旋阀型MR曲线的大MR比，并且MR比在1.4 nm处显示出最大值30%。在同一过程中制备的七个样品之间的MR比的离散度变得非常小。在射频等离子体的情况下，尽管在Al厚度为1.6nm时MR比为15％，但它随着Al厚度的减小而减小，并且在1.3nm处变得小于1％。样品之间的MR比的离散度比直流等离子体情况下的更大。这些结果表明，与射频等离子体相比，直流等离子体更适合Al层的氧化。然而，与射频等离子体情况相比，直流等离子体情况下的MR比随着偏压的增加而下降得更急剧，这意味着直流等离子体的氧化过程也应该得到改善。认为这些结果是由于Al层氧化程度和隧道势垒界面粗糙度的差异造成的。该隧道器件表现出良好的热稳定性，在真空中退火温度低于 300°C 时，MR 比不会发生变化。

项目成果

期刊论文数量（15）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Uncompensated spins in a micro-patterned CoFeB/MnIr exchange bias system

微图案 CoFeB/MnIr 交换偏置系统中的未补偿自旋

DOI：
发表时间：
2004
期刊：
Appl. Phys. Lett. 85-12
影响因子：
0
作者：
Jong-Ho Park;Mitsuhiko Mase;Shoji Kawahito;Masaaki Sasaki;Yasuo Wakamori;Yukihiro Ohta;T.Eimuller et al.
通讯作者：
T.Eimuller et al.

STM observation and magnetic anisotropy of MBE-Grown Fe/Pt superlattices with (111) and (001) orientations

(111) 和 (001) 取向 MBE 生长的 Fe/Pt 超晶格的 STM 观察和磁各向异性