双势垒磁性隧道结的磁电阻效应及其在自旋晶体管中的应用

利用磁控溅射方法沉积双势垒磁性隧道结多层膜, 其中Al-O势垒层由等离子体氧化1 nm厚的 金属铝膜方式制备，然后采用深紫外光曝光和Ar离子刻蚀技术、微加工制备出长短轴分别为 6和3 μm大小的椭圆形双势垒磁性隧道结（DBMTJ），并在室温和低温下对其自旋电子输运 特性进行了研究. DBMTJ的隧穿磁电阻(TMR)比值在室温和42 K分别达到27％和423％， 结电阻分别为136 kΩ·μm²和175 kΩ·μm²，并在实验中观 察到平行状 态下存在低电阻态及共振隧穿效应，反平行态下呈现高电阻态以及TMR随外加偏压或直流电 流的增加而发生振荡现象. 由此，设计了一种基于这种双势垒磁性隧道结隧穿特性的自旋晶 体管. 关键词： 双势垒磁性隧道结 隧穿磁电阻 共振隧穿效应 自旋晶体管

Magnetoresistance effect of double-barrier magnetic tunneling junction applied in spin transistors

The multilayer films of the double-barrier magnetic tunneling junctions (DBMTJs) were deposited by magnetron sputtering. The AlO_x insulator was forme d by plasma oxidizing aluminium. The photolithographic pattering procedure combin ed with Ar ion milling was used to microfabricate the DBMTJs with an ellipse of 　π×３×６μm². Magnetic transport properties of DBMTJs were invest igate d. The junctions show a resistance-area product about 136 kΩ·μm² and 175 kΩ·μm², a high tunneling magnetoresistance of 27% and 422% at 3 00 K and 42 K, respectively. A tunneling magnetoresistance oscillation phenome non with respect to the bias voltage was first observed in this experiment. We d esigned a few kind of spin transistors based on the spin-dependent resonant tunn eling effect of the DBMTJs.