Interface reflectivity of a superdiffusive spin current in ultrafast demagnetization and terahertz emission

The spin- and energy-dependent interface reflectivity of a ferromagnetic (FM) film in contact with a nonmagnetic (NM) film is calculated using a first-principles transport method and incorporated into the superdiffusive spin transport model to study the femtosecond laser-induced ultrafast demagnetiz...

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Bibliographic Details
Published in:Physical review. B 2020-01, Vol.101 (1), p.1, Article 014435
Main Authors: Lu, Wen-Tian, Zhao, Yawen, Battiato, Marco, Wu, Yizheng, Yuan, Zhe
Format: Article
Language:English
Subjects:
Aluminum
Demagnetization
Electromagnetic radiation
Electron spin
Emission
Ferromagnetic materials
First principles
Gold
Hot electrons
Interfaces
Nickel
Platinum
Reflectance
Spintronics
Transport
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Summary:The spin- and energy-dependent interface reflectivity of a ferromagnetic (FM) film in contact with a nonmagnetic (NM) film is calculated using a first-principles transport method and incorporated into the superdiffusive spin transport model to study the femtosecond laser-induced ultrafast demagnetization of Fe|NM and Ni|NM (NM = Au, Al, and Pt) bilayers. By comparing the calculated demagnetization with transparent and real interfaces, we demonstrate that the spin-dependent reflection of hot electrons has a noticeable influence on the ultrafast demagnetization and the associated terahertz (THz) electromagnetic radiation. In particular, a spin filtering effect is found at the Fe|NM interface that increases the spin current injected into the NM metal, which enhances both the resulting demagnetization and the resulting THz emission. This suggests that the THz radiation can be optimized by tailoring the interface, indicating a very large tunability.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.101.014435