Samsung Advanced Institute of Technology-SAIT, San #14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-Do 446-712, Korea.
Sci Rep. 2012;2:531. doi: 10.1038/srep00531. Epub 2012 Jul 25.
Magnetic damping of the spin, the decay rate from the initial spin state to the final state, can be controlled by the spin transfer torque. Such an active control of damping has given birth to novel phenomena like the current-driven magnetization reversal and the steady spin precession. The spintronic devices based on such phenomena generally consist of two separate spin layers, i.e., free and pinned layers. Here we report that the dipolar coupling between the two layers, which has been considered to give only marginal effects on the current driven spin dynamics, actually has a serious impact on it. The damping of the coupled spin system was greatly enhanced at a specific field, which could not be understood if the spin dynamics in each layer was considered separately. Our results give a way to control the magnetic damping of the dipolar coupled spin system through the external magnetic field.
自旋的磁阻尼，即从初始自旋态到最终态的衰减率，可以通过自旋转移扭矩来控制。这种对阻尼的主动控制产生了一些新的现象，如电流驱动的磁化反转和稳定的自旋进动。基于这些现象的自旋电子器件通常由两个独立的自旋层组成，即自由层和钉扎层。在这里，我们报告了两个层之间的偶极耦合，它虽然被认为对电流驱动的自旋动力学只有微小的影响，但实际上对其有严重的影响。在特定的磁场下，耦合自旋系统的阻尼大大增强，如果分别考虑每个层中的自旋动力学，这是无法理解的。我们的结果为通过外部磁场控制偶极耦合自旋系统的磁阻尼提供了一种方法。
