Shaped angular dependence of the spin-transfer torque and microwave generation without magnetic field
Shaped angular dependence of the spin-transfer torque and microwave generation without magnetic field
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DOI：
10.1038/nphys618
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发表时间：
2007-07-01
期刊：
影响因子：
19.6
通讯作者：
Fert, A.
中科院分区：
文献类型：
--
作者：
Boulle, O.;Cros, V.;Fert, A.
在微波频率范围内产生振荡是利用自旋转移现象的自旋电子学器件所期望的最重要的应用之一，自旋转移现象是由自旋极化电流对铁磁畴的磁化重定向。在这里，我们报告运输和微波功率测量专门设计的纳米柱，其中一个非标准的角度依赖的自旋转移力矩的理论模型预测。我们观察到一种新的电流诱导动力学，其特征在于在没有任何外加场的情况下大角度进动。这也是预测的模拟，包括一个“波浪形”的角度依赖的扭矩。这种类型的纳米柱能够在零外加磁场中产生微波振荡，可以代表一种有趣的方法来实现自旋转移振荡器。我们还强调我们的结果的理论意义上的角度依赖的扭矩。
The generation of oscillations in the microwave frequency range is one of the most important applications expected from spintronics devices exploiting the spin-transfer phenomenon, which is the reorientation of the magnetization of a ferromagnetic domain by spin-polarized current. Here we report transport and microwave power measurements on specially designed nanopillars, for which a nonstandard angular dependence of the spin-transfer torque is predicted by theoretical models. We observe a new kind of current-induced dynamics that is characterized by large angle precessions in the absence of any applied field. This is also predicted by simulations including a 'wavy' angular dependence of the torque. This type of nanopillar, which is able to generate microwave oscillations in zero applied magnetic field, could represent an interesting method for the implementation of spin-transfer oscillators. We also emphasize the theoretical implications of our results on the angular dependence of the torque.