Development of magnetic tunnel junctions using Heusler alloy and observation of spin-injected magnetization reversal

使用赫斯勒合金开发磁隧道结并观察自旋注入磁化反转

基本信息

批准号：
17206001
负责人：
MIYAZAKI Terunobu
金额：
$ 32.7万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

1. Fabrication of magnetic tunnel junctions using epitaxial Heusler alooy electrodes Large tunnel magneto-resistance (TMR) ratios of 217% at room temperature and 753% at low temperature have been successfully observed in a magnetic tunnel junction (MTJ) using a high quality Heusler alloy electrode and an MgO crystalline barrier. The structure of the MTJ was Co2MnSi/MgO/CoFe. This observed TMR ratio is highest among the MTJs using Heusler alloy electrodes. Moreover, conductance-voltage property of the MTJ investigated in detail indicates that the origin of the large TMR was coherent tunneling process through the crystalline MgO barrier.2. Micro-fabrication of MTJs and Observation of spin-injected magnetization reversal Spin-injected magnetization reversal has been successfully observed in the micro-fabricated CoFeB/MgO/CoFeB-MTJs using (Co_<50>Fe_<50>)_<100-x>B_x (x=20, 25, 30, thickness d=2 nm) switching layers. We found from this result that the switching current density depended on magnetization, damping constant and spin polarization of the ferromagnetic layer as expected by theory and reducing of magnetization and damping constant was quite effective to decrease the switching current density.3. Magnetic damping constant α Magnetic damping constants in various ferromagnetic thin films were investigated systematically by FMR technique. Moreover, a measurement technique for estimation of damping constants in MTJs has been established. As a result, we found that the damping constant of 2nm thick CoFeB film was five times larger than that of bulk CoFeB and the neighboring layer of the switching layer influence the damping constant of the switching layer.

1。使用外延小母牛抗元电极在室温下使用217％和低温下的753％的磁性隧道连接，在使用高质量的Heusler Alloy Alloy Electode Electode Electode和Mgo Crystalline Crystalline barrier中成功观察到了低温下的753％。 MTJ的结构为CO2MNSI/MGO/COFE。使用Heusler合金电极，在MTJ中观察到的TMR比最高。此外，已详细研究的MTJ的电导 - 电压特性表明，大型TMR的起源是通过晶体MGO屏障的相干隧穿过程。2。 Micro-fabrication of MTJs and Observation of spin-injected magnetization reversal Spin-injected magnetization reversal has been successfully observed in the micro-fabricated CoFeB/MgO/CoFeB-MTJs using (Co_<50>Fe_<50>)_<100-x>B_x (x=20, 25, 30, thickness d=2 nm) switching layers.从这个结果中我们发现，开关电流密度取决于磁化，舞蹈常数和铁磁层的自旋极化，这是理论上预期的，磁化和舞蹈常数的减少对于降低开关电流密度非常有效。3。通过FMR技术系统地研究了各种铁磁薄膜中磁阻尼常数α磁阻尼常数。此外，已经建立了一种用于估计MTJ舞蹈常数的测量技术。结果，我们发现2nm厚的COFEB膜的舞蹈常数比散装COFEB大五倍，而开关层的相邻层影响开关层的舞蹈常数。