Unifying femtosecond and picosecond single-pulse magnetic switching in Gd-Fe-Co
Unifying femtosecond and picosecond single-pulse magnetic switching in Gd-Fe-Co
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DOI：
10.1103/physrevb.103.104422
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发表时间：
2020-04
影响因子：
3.7
通讯作者：
F. Jakobs;T. Ostler;C. Lambert;Yang Yang-Yang;S. Salahuddin;Richard B. Wilson;J. Gorchon;J. Bokor;U. Atxitia
中科院分区：
文献类型：
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作者：
F. Jakobs;T. Ostler;C. Lambert;Yang Yang-Yang;S. Salahuddin;Richard B. Wilson;J. Gorchon;J. Bokor;U. Atxitia
关于GdFeCo合金单脉冲磁开关背后的物理机制仍有许多问题有待解决。唯象模型表明，飞秒尺度的交换弛豫亚晶格磁化之间的驱动机制切换。最近的观察GdFeCo的热致开关，同时使用几个皮秒光脉冲以及电流脉冲提出了质疑，以前的理解。这就提出了一个问题，即在飞秒和皮秒尺度上是否存在相同的开关机制。在这项工作中，我们的目标是填补这一空白的理解背后的热单脉冲开关的开关机制。为此，我们实验研究了GdFeCo合金的热单脉冲开关，为广泛的系统参数，如组成，激光功率和脉冲持续时间。我们提供了一个定量描述的开关动力学使用原子自旋动力学的方法，在广泛的参数和时间尺度，范围从飞秒到皮秒之间的模型和我们的实验具有良好的一致性。此外，我们发现不同的元素特定的阻尼参数作为一个关键成分的开关与长皮秒脉冲，并认为，开关与脉冲持续时间长达15皮秒是可能的，由于低阻尼常数的Gd。我们的研究结果可以很容易地扩展到加速动力学在其他情况下，亚铁磁GdFeCo合金已经被证明显示出快速和节能的过程，例如畴壁运动的轨道和自旋电子器件中的自旋轨道转矩切换。
Many questions are still open regarding the physical mechanisms behind the magnetic switching in GdFeCo alloys by single optical pulses. Phenomenological models suggest a femtosecond scale exchange relaxation between sublattice magnetization as the driving mechanism for switching. The recent observation of thermally induced switching in GdFeCo by using both several picosecond optical laser pulse as well as electric current pulses has questioned this previous understanding. This has raised the question of whether or not the same switching mechanics are acting at the femo- and picosecond scales. In this work, we aim at filling this gap in the understanding of the switching mechanisms behind thermal single-pulse switching. To that end, we have studied experimentally thermal single-pulse switching in GdFeCo alloys, for a wide range of system parameters, such as composition, laser power and pulse duration. We provide a quantitative description of the switching dynamics using atomistic spin dynamics methods with excellent agreement between the model and our experiments across a wide range of parameters and timescales, ranging from femtoseconds to picoseconds. Furthermore, we find distinct element-specific damping parameters as a key ingredient for switching with long picosecond pulses and argue, that switching with pulse durations as long as 15 picoseconds is possible due to a low damping constant of Gd. Our findings can be easily extended to speed up dynamics in other contexts where ferrimagnetic GdFeCo alloys have been already demonstrated to show fast and energy-efficient processes, e.g. domain-wall motion in a track and spin-orbit torque switching in spintronics devices.