期刊
ADVANCED MATERIALS INTERFACES
卷 9, 期 36, 页码 -出版社
WILEY
DOI: 10.1002/admi.202201675
关键词
spin Hall angles; spin-to-charge-current conversion; terahertz emission spectroscopy; transition-metal dichalcogenides (TMDCs); ultrafast spin current injections
资金
- European Union [681917, 766566]
- DFG priority program INTEREST (project ITISA)
- Czech Science Foundation through Project GA CR [21-28876J]
- Grant Agency of the Charles University [SVV-2022-260590]
- Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) [TRR 288 - 422213477]
- Generalitat Valenciana [CIDEGENT/2021/005]
- Julich Supercomputing Centre [jiff40]
- Projekt DEAL
- German Research Foundation through the collaborative research center [SFB TRR 227, 328545488]
This study investigates spin-to-charge current conversion in transition-metal dichalcogenide NbSe2 using terahertz emission spectroscopy, revealing that the conversion mainly originates from the bulk of NbSe2 with the opposite, negative spin Hall angle compared to Pt.
Transition-metal dichalcogenides (TMDCs) are an aspiring class of materials with unique electronic and optical properties and potential applications in spin-based electronics. Here, terahertz emission spectroscopy is used to study spin-to-charge current conversion (S2C) in the TMDC NbSe2 in ultra-high-vacuum-grown F|NbSe2 thin-film stacks, where F is a layer of ferromagnetic Fe or Ni. Ultrafast laser excitation triggers an ultrafast spin current that is converted into an in-plane charge current and, thus, a measurable THz electromagnetic pulse. The THz signal amplitude as a function of the NbSe2 thickness shows that the measured signals are fully consistent with an ultrafast optically driven injection of an in-plane-polarized spin current into NbSe2. Modeling of the spin-current dynamics reveals that a sizable fraction of the total S2C originates from the bulk of NbSe2 with the opposite, negative sign of the spin Hall angle as compared to Pt. By a quantitative comparison of the emitted THz radiation from F|NbSe2 to F|Pt reference samples and the results of ab initio calculations, it is estimated that the spin Hall angle of NbSe2 for an in-plane polarized spin current lies between -0.2% and -1.1%, while the THz spin-current relaxation length is of the order of a few nanometers.
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