Spintronic THz Wave Emitter: an approach from Topological Weyl Semimetal Heusler alloys

自旋电子太赫兹波发射器：拓扑外尔半金属赫斯勒合金的一种方法

基本信息

批准号：
22K14586
负责人：
MANDAL Ruma
金额：
$ 2.91万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Early-Career Scientists
财政年份：
2022
资助国家：
日本
起止时间：
2022-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-22K14586/
关键词：
THz spectroscopy Weyl semimetal spintronics anomalous Hall effect Weyl Smeimetal Spintronics Anomalous Hall Effect

项目摘要

To achieve the research objectives, I investigated the THz emission from Weyl Heusler alloys Co2MnGa. I have obtained systematic data for the THz emission in Co2MnGa with different chemical ordering. According to the past research it was believed that in a single layer ferromagnet (not Weyl semimetals) the laser-excited electrons inside the ferromagnetic layer generates a back-flow current due to back scattering from substrate or capping layer which emits a THz wave due to anomalous Hall effect (AHE). Such back-scattering process strongly depends on the structural properties like thickness, roughness, and etc. Thus, I also focused on thickness dependence of the THz emission from Co2MnGa films to gain insight into the mechanism of the back scattering-induced THz emission via AHE. For thin regime of Co2MnGa films grown on MgO substrates and capped by the MgO layers, I found the strong signature that the origin of the THz emission was AHE which was enhanced by Weyl nature in Co2MnGa. In addition, I have investigated the composition dependence of the THz emission of Co2MnGa to clarify how the Wyle point location with respect to the Fermi level influences the THz emission. Those results were discussed in several conference meetings and the paper was submitted.

为了实现研究目标，我研究了 Weyl Heusler 合金 Co2MnGa 的太赫兹发射。我获得了具有不同化学顺序的 Co2MnGa 中太赫兹发射的系统数据。根据过去的研究，人们认为，在单层铁磁体（不是韦尔半金属）中，铁磁层内的激光激发电子由于基底或覆盖层的反向散射而产生回流电流，基底或覆盖层发射太赫兹波，这是由于反常霍尔效应（AHE）。这种背向散射过程很大程度上取决于厚度、粗糙度等结构特性。因此，我还重点研究了 Co2MnGa 薄膜太赫兹发射的厚度依赖性，以深入了解通过 AHE 背向散射引起的太赫兹发射的机制。对于在 MgO 基底上生长并由 MgO 层覆盖的 Co2MnGa 薄膜的薄区域，我发现太赫兹发射的来源是 AHE 的强烈特征，而 Co2MnGa 中的 Weyl 性质增强了 AHE。此外，我还研究了 Co2MnGa 太赫兹发射的成分依赖性，以阐明怀尔点相对于费米能级的位置如何影响太赫兹发射。这些结果在几次会议上进行了讨论，并提交了论文。