Fe₃GeTe₂-based Magnetic Van der Waals heterostructures for Valleytronics applications
Jia-Xin Li1*, Wei-Qing Li1, Sheng-Hsiung Hung2, Po-Liang Chen1, Yueh-Chiang Yang3, Tian-Yun Chang1, Po-Wen Chiu3,4, Horng-Tay Jeng2,5,6, Chang-Hua Liu1,3
1Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan
2Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
3Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan
4Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
5Institute of Physics, Academia Sinica, Taipei, Taiwan
6Physics Division, National Center for Theoretical Sciences, Hsinchu, Taiwan
* Presenter:Jia-Xin Li, email:ssleep66@gmail.com
The monolayer transition metal dichalcogenides (TMDs) are promising for valleytronics applications, due to their large spin-orbit coupling and loss of inversion symmetry. So far, numerous works have shown the optical control of the valley degree of freedom of TMDs. But to electrical control of this degree of freedom remains challenging. Here, we demonstrate the novel van der Waals heterostructures that incorporate a monolayer WSe₂ integrated with an ultrathin Fe₃GeTe₂ (FGT) magnetic contact. The exploited magnetic contact could inject spin-polarized carriers into a monolayer TMD, leading to valley-dependent polarization, as confirmed by our helicity-dependent electroluminescence and reflective magnetic circular dichroism measurements. In addition, our measurements indicate that injecting spin-polarized holes from FGT into WSe₂ can more effectively lead to valley polarization, compared with injecting spin-polarized electrons from FGT. Based on our density functional theory calculations, we reveal such phenomenon is related to the unique electronic structure of FGT.

Keywords: transition-metal dichalcogenides, valleytronics, 2D magnets, Electroluminescence, van der Waals heterostructure