Ultrafast magnetization enhancement in metallic multilayers driven by superdiffusive spin current
Ultrafast magnetization enhancement in metallic multilayers driven by superdiffusive spin current
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DOI：
10.1038/ncomms2029
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发表时间：
2012-09-01
影响因子：
16.6
通讯作者：
Oppeneer, Peter M.
中科院分区：
文献类型：
--
作者：
Rudolf, Dennis;La-O-Vorakiat, Chan;Oppeneer, Peter M.
揭示控制超快电荷和自旋动力学的物理机制对于理解相关物质以及基于超快自旋的电子学的基本限制至关重要。磁性材料中的自旋动力学可以由超短光脉冲驱动，从而在几百飞秒内导致磁化强度的瞬态下降。然而，对飞秒自旋动力学的全面理解仍然是难以捉摸的。在这里，我们使用Ni/Ru/Fe磁三层在空间上分离自旋动力学，其中Ni和Fe层可以是铁磁或反铁磁耦合的。用激光脉冲激励两层，同时探测Ni层和Fe层的磁化响应，我们惊奇地发现，当两层磁化初始平行排列时，Ni层的光诱导退磁会瞬间增强Fe层的磁化。我们的观察结果可以用激光在两层之间产生的超扩散自旋电流来解释。
Uncovering the physical mechanisms that govern ultrafast charge and spin dynamics is crucial for understanding correlated matter as well as the fundamental limits of ultrafast spin-based electronics. Spin dynamics in magnetic materials can be driven by ultrashort light pulses, resulting in a transient drop in magnetization within a few hundred femtoseconds. However, a full understanding of femtosecond spin dynamics remains elusive. Here we spatially separate the spin dynamics using Ni/Ru/Fe magnetic trilayers, where the Ni and Fe layers can be ferroor antiferromagnetically coupled. By exciting the layers with a laser pulse and probing the magnetization response simultaneously but separately in Ni and Fe, we surprisingly find that optically induced demagnetization of the Ni layer transiently enhances the magnetization of the Fe layer when the two layer magnetizations are initially aligned parallel. Our observations are explained by a laser-generated superdiffusive spin current between the layers.