有关新型磁随机存储器的新材料及新器件的研究

As the development of modern information society, people demand more and more on the memory, especially on the storage density and speed. To develop new type of memory with ultra-high speed and storage density is the primary target of information community. Magnetic Random Access Memory (MRAM) has the properties of non-volatile, long life-time, high speed, and radiation safe, etc. It can be used in a lot of field, including embedded system, network and data storage, industrial automation, automobile and aerospace industry. Right now, the bottleneck of MRAM is the high current density required by switching the magnetic free layer in the MTJ structure, which limits the minimization of MRAM, and also consumes a lot of energy. In this proposal, we are going to use the electrical voltage to control the magnetic anisotropic energy. Using the electrical field, we can tune magnetic easy axis of the free layer between the in-plane and out-of-plane, the magnetization can then process under thermal activation. Thus the magnetization can be flipped after process 180 degree under proper timing. We have also proposed to use materials with strong spin-orbit coupling, for example, topological insulators, to make new prototype MRAM devices. The operation principle is first by passing current in TIs, spin current will be generated at the interface by spin Hall effect. Second through spin transfer torque, the spin current can flip the magnetization of the free layer. Due to the very big spin Hall angle, we expect to dramatically lower the critical current density to flip the magnetization.

现代信息社会的高速发展，对存储器的存储密度和存储速度提出了越来越高的要求。开发新一代的具有超高存储密度和速度的存储器，为当前研究的核心内容。磁随机存储器MRAM具有存储数据非易失性、寿命长、速度快、抗辐射等诸多优点，在嵌入式计算、网络和数据存储、工业自动化、汽车和航空航天等重要的民生、国防领域具有巨大的应用价值。目前限制MRAM的一个巨大的瓶颈为MTJ中写入电流密度过大，这给产品的微缩化带来限制，并且使得产品的能耗较高，无法进一步提高存储密度。本项目将会利用电场直接控制磁性自由层中的垂直各向异性能。实现电场下，自由层易轴在平面和垂直方向的改变，从而通过电场控制磁性层的翻转。另外我们还打算利用最新的强自旋轨道耦合材料，比如说拓扑绝缘体，来构建新型的MRAM器件。利用其自旋霍尔效应，通过自旋转移力矩来翻转磁性自由层，从而极大地降低临界电流密度。

现代信息社会的高速发展，对存储器的存储密度和存储速度提出了越来越高的要求。开发新一代的具有超高存储密度和速度的存储器，为当前研究的核心内容。磁随机存储器MRAM具有存储数据非易失性、寿命长、速度快、抗辐射等诸多优点，在嵌入式计算、网络和数据存储、工业自动化、汽车和航空航天等重要的民生、国防领域具有巨大的应用价值。目前限制MRAM的一个巨大的瓶颈为MTJ中写入电流密度过大，这给产品的微缩化带来限制，并且使得产品的能耗较高，无法进一步提高存储密度。本项目将会利用电场直接控制磁性自由层中的垂直各向异性能。实现电场下，自由层易轴在平面和垂直方向的改变，从而通过电场控制磁性层的翻转。另外我们还打算利用最新的强自旋轨道耦合材料，比如说拓扑绝缘体，来构建新型的MRAM器件。利用其自旋霍尔效应，通过自旋转移力矩来翻转磁性自由层，从而极大地降低临界电流密度