IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.
Max Planck Institute for Microstructure Physics, Weinberg 2, D-06120 Halle (Saale), Germany.
Nat Commun. 2017 Jun 28;8:16004. doi: 10.1038/ncomms16004.
Rabi oscillations describe the process whereby electromagnetic radiation interacts coherently with spin states in a non-equilibrium interaction. To date, Rabi oscillations have not been studied in one of the most common spin ensembles in nature: spins in ferromagnets. Here, using a combination of femtosecond laser pulses and microwave excitations, we report the classical analogue of Rabi oscillations in ensemble-averaged spins of a ferromagnet. The microwave stimuli are shown to extend the coherence-time resulting in resonant spin amplification. The results we present in a dense magnetic system are qualitatively similar to those reported previously in semiconductors which have five orders of magnitude fewer spins and which require resonant optical excitations to spin-polarize the ensemble. Our study is a step towards connecting concepts used in quantum processing with spin-transport effects in ferromagnets. For example, coherent control may become possible without the complications of driving an electromagnetic field but rather by using spin-polarized currents.
拉比振荡描述了电磁辐射与非平衡相互作用中自旋态相干相互作用的过程。迄今为止，拉比振荡尚未在自然界中最常见的自旋体之一中进行研究：铁磁体中的自旋。在这里，我们使用飞秒激光脉冲和微波激发的组合，报告了铁磁体中自旋集体平均的拉比振荡的经典类似物。结果表明，微波刺激会延长相干时间，从而导致共振自旋放大。我们在密集磁系统中呈现的结果与以前在半导体中报道的结果定性相似，半导体中的自旋数量少五个数量级，并且需要共振光激发来使集体自旋极化。我们的研究是朝着将量子处理中使用的概念与铁磁体中的自旋输运效应联系起来的一步。例如，相干控制可能成为可能，而无需驱动电磁场的复杂性，而是通过使用自旋极化电流。
