Tong Mingyu, Hu Yuze, Wang Zhenyu, Zhou Tong, Xie Xiangnan, Cheng Xiang'ai, Jiang Tian
National Innovation Institute of Defense Technology, Academy of Military Sciences PLA China, Beijing 100010, China.
Beijing Academy of Quantum Information Sciences, Beijing 100193, China.
Nano Lett. 2021 Jan 13;21(1):60-67. doi: 10.1021/acs.nanolett.0c03079. Epub 2020 Dec 17.
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.
太赫兹（THz）辐射的增强对于太赫兹探测和成像的实现具有极其重要的意义。然而，目前的太赫兹技术远不足以实现高性能和室温下的太赫兹源。幸运的是，具有自旋动量锁定狄拉克表面态的拓扑绝缘体（TIs）有望展现出高太赫兹发射效率。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，展示了一种Rashba态增强的自旋电子太赫兹发射器的新概念。我们发现太赫兹发射强度随重金属中间层厚度而变化，当插入精心设计厚度的重金属层时，与FM/TI相比，强度可提高1.98倍。太赫兹辐射的增强归因于HM/TI界面处Rashba分裂和拓扑表面态的叠加效应。这些结果为在基于TI的磁性异质结构中实现自旋电子太赫兹发射器提供了新的可能性。
