THz-Driven Ultrafast Spin-Lattice Scattering in Amorphous Metallic Ferromagnets
THz-Driven Ultrafast Spin-Lattice Scattering in Amorphous Metallic Ferromagnets
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DOI：
10.1103/physrevlett.117.087205
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发表时间：
2016-08-17
影响因子：
8.6
通讯作者：
Durr, H. A.
中科院分区：
文献类型：
--
作者：
Bonetti, S.;Hoffmann, M. C.;Durr, H. A.
我们使用单周期太赫兹场和飞秒磁光克尔效应，分别激发和探测两种不同晶格结构的薄膜铁磁体：晶态Fe和非晶态CoFeB的磁化动力学。我们观察到的Landau-Lifshitz扭矩磁化动力学在这两个系统中的可比幅度，但只有非晶样品显示超快退磁所造成的自旋晶格去极化的太赫兹诱导的超快自旋电流。定量建模表明，这种自旋晶格散射事件发生在类似的时间尺度比传统的自旋守恒电子散射（类似于30 fs）。这比光学激光诱导的去磁要快得多。太赫兹电导率测量指向非晶CoFeB中的晶格无序的影响，作为增强的自旋-晶格散射的驱动力。
We use single-cycle THz fields and the femtosecond magneto-optical Kerr effect to, respectively, excite and probe the magnetization dynamics in two thin-film ferromagnets with different lattice structures: crystalline Fe and amorphous CoFeB. We observe Landau-Lifshitz-torque magnetization dynamics of comparable magnitude in both systems, but only the amorphous sample shows ultrafast demagnetization caused by the spin-lattice depolarization of the THz-induced ultrafast spin current. Quantitative modeling shows that such spin-lattice scattering events occur on similar time scales than the conventional spin conserving electronic scattering (similar to 30 fs). This is significantly faster than optical laser-induced demagnetization. THz conductivity measurements point towards the influence of lattice disorder in amorphous CoFeB as the driving force for enhanced spin-lattice scattering.