Fe-MgO颗粒膜低的室温自旋转移矩临界电流密度

降低自旋转移矩效应（STT）的室温临界电流密度是该效应实用化的一个关键，国际上STT的研究都集中在自旋阀和磁隧道结两种薄膜结构中，报道的STT室温临界电流密度处于兆安每平方厘米量级（有一个例外，但需额外加电场协助），限制了它的应用。我们前期工作在Fe-MgO颗粒膜中观察到室温临界电流密度低至4.2千安每平方厘米的自旋转移矩效应。本项目旨在前期工作基础上利用改变生长条件、退火和光刻等方法来调节Fe-MgO颗粒膜中Fe含量、Fe颗粒尺寸、Fe颗粒间MgO绝缘材料的厚度和样品尺寸等物理参数,研究Fe-MgO颗粒膜STT效应和室温临界电流密度与这些物理参数的关系,寻求更低STT室温临界电流密度；采用增加Fe颗粒尺寸和磁场中真空退火等方法来使该STT效应具有显著的电滞特性；研究该STT效应和临界电流密度与温度的关系,揭示其物理机制和热稳定性；探索有助于Fe-MgO颗粒膜自旋转移矩效应实用化的条件。

From a practical point of view, a critical issue for the spin-transfer torque effect is the reduction of the critical switching current density Jc.Spin-transfer torque effect was observed in spin valves and tunnel junctions at room temperature, but the reported Jc is in the range of 1 MA/cm2, which is too high for practical applications.Recently, we achieved ultralow critical switching current density Jc about 4.2 KA/cm2 for spin transfer in Fe-MgO nanscale granular film at room temperature. In this project, the Fe fraction, the Fe particle size and MgO thickness of Fe-MgO granular film will be adjusted by changing growing conditions. Then the relation between above factors and the spin-transfer torque effect of Fe-MgO granular film will be investigated, and lower critical switching current density will be achieved. Electric hysteresis of the spin-transfer torque effect will be obtained.In order to reveal the physical mechanism and thermal stability, the temperature dependence of the spin-transfer torque effect will be investigated. The application condition of spin-transfer torque effect of Fe-MgO granular film will be explored.