Fablication of novel spintronic devices using MTJs with magnetic insulators

在自旋电子学研究领域，MRAM和STT-RAM备受关注。在这些器件中，磁隧道结(MTJ)是最重要的元件。STT-RAM使用自旋扭矩转移磁化反转来切换极低功率的磁化。2010年，SLonczewski提出，磁性绝缘体中自旋波产生的自旋电流有效地逆转了磁化强度。然而，具有磁性氧化物绝缘体的MTJ至今未见报道。在本研究中，我们利用反应分子束外延技术制备了尖晶石型铁氧体外延材料，从RHEED和AFM观察，铂比铬和金更适合作为铁氧体和铁氧体之间的插入层。关于磁化过程，通过插入非磁性层来增强饱和场。电子束光刻制作的MTJ器件具有70%的TMR效应。

In the spintronics research fields, MRAM and STT-RAM have attracted much attention. In the devices, magnetic tunnel junctions (MTJs) are the most impotant elements. The STT-RAM employs the spin torque transfer magnetization reversal to switch the magnetization on very low power. In 2010, Slonczewski proposed that the magnetization is reversed effectively by the spin current generated by spin wave in magnetic insulator. However, the MTJs with magnetic oxide insulator are not reported so far. In this study, we fabricated the epitaxial MgO-MTJs with spinel ferrite oxide using reactive molecular beam epitaxy.From the RHEED and AFM observations, Pt is more appropriate for the insertion layer between Fe and ferrite layers than Cr and Au. Regarding the magnetization process, the saturation field was enhanced by insertion of the non-magnetic layer. The MTJ devices fabricated by e-beam lithography exhibited TMR effects of 70%.