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arXiv 2104.04780cond-mat.mes-hall
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基于反铁磁畴壁的自旋霍尔纳米振荡器

Spin-Hall nanooscillator based on an antiferromagnetic domain wall

Roman V. Ovcharov, Elena G. Galkina, Boris A. Ivanov, Roman S. Khymyn

AI总结:

提出一种基于易轴反铁磁体畴壁的高频自旋霍尔纳米振荡器,利用自旋电流激发 Néel 矢量锥形进动,实现可调至 THz 且阈值电流趋零的稳健交流输出。

摘要:

我们在此提出一种高频自旋霍尔纳米振荡器,它基于位于易轴各向异性型反铁磁体中的简单磁织构(例如畴壁)。我们表明,沿各向异性轴极化的自旋电流会在此类畴壁中激发 Néel 矢量的锥形进动,从而能够获得稳健的交流输出信号;这与均匀单轴反铁磁体中的平面进动相反,后者很难实现交流输出。自振荡频率可通过所施加电流方便地调谐,最高可达 THz 范围,并且对于纯单轴反铁磁体,阈值电流趋于零。通过微磁模拟,我们证明畴壁的钉扎对振荡器设计至关重要,而这可通过自由层的纳米收缩布局来实现。

英文摘要:

We propose here a high-frequency spin-Hall nano-oscillator based on a simple magnetic texture, such as a domain wall, located in an antiferromagnet with easy-axis anisotropy type. We show that the spin current, polarized along the anisotropy axis, excites a conical precession of the Néel vector in such a domain wall, which allows obtaining a robust ac output signal, -- contrary to the planar precession in an uniform uniaxial antiferromagnet, where ac output is hard to achieve. The frequency of the auto-oscillations is easily tunable by the applied current up to the THz range, and the threshold current vanishes for pure uniaxial antiferromagnet. By micro-magnetic simulations, we demonstrate that the pinning of the domain wall is crucial for the oscillator design, which can be achieved in nano-constriction layout of the free layer.

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