Enhanced Terahertz Radiation by Efficient Spin-to-Charge Conversion in Rashba-Mediated Dirac Surface States,Nano Letters

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Enhanced Terahertz Radiation by Efficient Spin-to-Charge Conversion in Rashba-Mediated Dirac Surface States
Nano Letters ( IF 9.6 ) Pub Date : 2020-12-17 , DOI: 10.1021/acs.nanolett.0c03079
Mingyu Tong , Yuze Hu , Zhenyu Wang _{1,

2} , Tong Zhou ₁ , Xiangnan Xie , Xiang’ai Cheng , Tian Jiang

Affiliation

The enhancement of terahertz (THz) radiation is of extreme significance for the realization of the THz probe and imaging. However, present THz technologies are far from being enough to realize high-performance and room-temperature THz sources. Fortunately, topological insulators (TIs), with spin-momentum-locked Dirac surface states, are expected to exhibit a high terahertz emission efficiency. In this work, the novel concept of a Rashba-state-enhanced spintronic THz emitter is demonstrated on the basis of ferromagnet/heavy metal/topological insulator (FM/HM/TI) heterostructure. We find that the THz emission intensity changes as a function of HM interlayer thickness, and a 1.98 times higher intensity compared to that of FM/TI can be achieved when a meticulously designed thickness of the HM layer is inserted. The improvement of terahertz radiation is ascribed to the additive effect of Rashba splitting and topological surface states at the HM/TI interface. These results offer new possibilities for realizing spintronic THz emitters in TI-based magnetic heterostructures.

中文翻译：

在Rashba介导的Dirac表面态中通过有效的自旋电荷转换增强了太赫兹辐射

太赫兹（THz）辐射的增强对于实现THz探头和成像至关重要。但是，目前的太赫兹技术远远不足以实现高性能和室温太赫兹源。幸运的是，具有自旋动量锁定Dirac表面态的拓扑绝缘体（TI）有望展现出很高的太赫兹发射效率。在这项工作中，基于铁磁体/重金属/拓扑绝缘体（FM / HM / TI）异质结构展示了Rashba态增强的自旋电子THz发射器的新颖概念。我们发现，THz发射强度随HM中间层厚度的变化而变化，当插入精心设计的HM层厚度时，可以实现比FM / TI高1.98倍的强度。太赫兹辐射的改善归因于拉什巴分裂和HM / TI界面处的拓扑表面状态的加和效应。这些结果为在基于TI的磁异质结构中实现自旋电子THz发射器提供了新的可能性。

更新日期：2021-01-13

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