论文标题

在化学无序的铁磁单层中观察强大阻尼状旋转轨道扭矩

Observation of strong bulk damping-like spin-orbit torque in chemically disordered ferromagnetic single layers

论文作者

Zhu, Lijun, Zhang, Xiyue S., Muller, David A., Ralph, Daniel C., Buhrman, Robert A.

论文摘要

强阻尼状自旋轨道扭矩(τDL)具有极大的潜力,可以实现超快的磁性记忆,振荡器和逻辑。到目前为止,施加在薄膜磁铁上的报道的τdl必须是由外部产生的自旋电流或非中心对称GAMNAS单晶的内部非平衡自旋极化产生的。在这里,我们第一次表现出非常强,意外的τdl,来自化学无序的,面部中心地带COPT的铁磁单层中的当前流动。我们确定新颖的τdl是庞大的效应,每单位电流密度的强度与COPT厚度单调增加,并且对Copt表面上的自旋水槽的存在不敏感。该τdl很可能是由与强旋霍尔效应(SHE)相关的净横向自旋极化引起的,而材料中没有可检测到的长距离不对称。这些结果扩大了自旋能源的范围,并为开发基于单层的旋转旋转记忆,振荡器和逻辑技术提供了新的途径。

Strong damping-like spin-orbit torque (τDL) has great potential for enabling ultrafast energy-efficient magnetic memories, oscillators, and logic. So far, the reported τDL exerted on a thin-film magnet must result from an externally generated spin current or from an internal non-equilibrium spin polarization in noncentrosymmetric GaMnAs single crystals. Here, we for the first time demonstrate a very strong, unexpected τDL from current flow within ferromagnetic single layers of chemically disordered, face-centered-cubic CoPt. We establish that the novel τDL is a bulk effect, with the strength per unit current density increasing monotonically with the CoPt thickness, and is insensitive to the presence or absence of spin sinks at the CoPt surfaces. This τDL most likely arises from a net transverse spin polarization associated with a strong spin Hall effect (SHE), while there is no detectable long-range asymmetry in the material. These results broaden the scope of spin-orbitronics and provide a novel avenue for developing single-layer-based spin-torque memory, oscillator, and logic technologies.

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