Magnetization dynamics of synthetic MRAM free layers: coupled precession and ultra fast magnetization reversal strategies

合成 MRAM 自由层的磁化动力学：耦合进动和超快磁化反转策略

• 批准号: 27175164
• 负责人: Professor Dr. Günter Reiss
• 金额: --
• 依托单位: Fachbereich 2.5 - Halbleiterphysik und Magnetismus
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/27175164?language=en
• 关键词: Magnetization; dynamics; synthetic; MRAM; free

The aim of this work is to study the magnetization dynamics of microscopic synthetic antiferromagnets (SyAF) cells on the 10 ps time scale. SyAF consist of two ferromagnetic thin films FM1, FM2 separated by an ultra thin non-magnetic exchange coupling layer (CL) which induces an antiparallel alignment of the magnetization M1, M2 of the two ferromagnets. Such SyAF are now used as the storage layer (or ¿free layer¿) in magnetic random access memories (MRAM) and magnetic logic. So far, the important question of the maximum write rate of a SyAF free layer device has not been answered. How fast can the magnetization of a SyAF free layer cell be reversed? To answer this question the coupled precessional dynamics of the magnetization M1, M2 of the two ferromagnets in the SyAF and their dependence on device parameters is studied. To get a complete picture of the SyAF dynamics the time resolved trajectories of the magnetization M1,M2 of both ferromagnets FM1, FM2, are derived from time resolved magneto transport measurements. For this purpose a novel sample design - consisting of a SyAF sandwiched between a magnetic tunnel junction and a spin valve ¿ is developed. It allows for the first time to derive the magnetization dynamics of both two ferromagnets FM1, FM2 independently in an all electrical setup. This experiment allows to fully track the magnetization dynamics of the SyAF in sub micron magnetic memory cells. The dynamics are studied for different sample parameters (exchange coupling strength, spin compensation, etc¿) and are compared to numerical simulations. Recently proposed ultra fast precessional SyAF MRAM reversal schemes are tested.

本工作的目的是研究10 ps时间尺度上的微观合成反铁磁体（SyAF）细胞的磁化动力学。SyAF由两个铁磁薄膜FM 1、FM 2组成，这两个铁磁薄膜由超薄非磁性交换耦合层（CL）分隔开，该层引起两个铁磁体的磁化M1、M2的反平行排列。这种SyAF现在被用作磁性随机存取存储器（MRAM）和磁性逻辑中的存储层（或自由层）。到目前为止，SyAF自由层器件的最大写入速率这一重要问题还没有得到回答。SyAF自由层单元的磁化反转速度有多快？为了回答这个问题的耦合旋进动力学的两个铁磁体在SyAF的磁化M1，M2和它们对设备参数的依赖性进行了研究。为了获得SyAF动力学的完整图像，两个铁磁体FM 1、FM 2的磁化强度M1、M2的时间分辨轨迹是从时间分辨磁输运测量中推导出来的。为此，开发了一种新颖的样品设计-由夹在磁性隧道结和自旋阀之间的SyAF组成。它允许第一次推导出两个铁磁体FM 1，FM2的磁化动力学独立地在一个所有的电气设置。该实验允许在亚微米磁存储器单元中完全跟踪SyAF的磁化动力学。动力学研究不同的样品参数（交换耦合强度，自旋补偿等），并进行了比较，数值模拟。最近提出的超快速进动SyAF MRAM反转方案进行了测试。