Terahertz spin-to-charge conversion by interfacial skew scattering in metallic bilayers

Oliver Gueckstock*, Lukas Nadvornik*, Martin Gradhand, Tom Sebastian Seifert, Genaro Bierhance, Reza Rouzegar, Martin Wolf, Mehran Vafaee, Joel Cramer, Maria Andromachi Syskaki, Georg Woltersdorf, Ingrid Mertig, Gerhard Jacob, Mathias Kläui, Tobias Kampfrath

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

7 Citations (Scopus)
15 Downloads (Pure)

Abstract

The efficient conversion of spin to charge transport and vice versa is of major relevance for the detection and generation of spin currents in spin-based electronics. Interfaces of heterostructures are known to have a marked impact on this process. Here, we use terahertz (THz) emission spectroscopy to study ultrafast spin-to-charge-current conversion (S2C) in about 40 prototypical F|N bilayers consisting of a ferromagnetic layer F (e.g. Ni81Fe19, Co or Fe) and a nonmagnetic layer N with strong (Pt) or weak (Cu, Al) spin-orbit coupling. Varying the structure of the F/N interface allows us to drastically change the amplitude and even invert the polarity of the THz charge current. Remarkably, when N is a material with small spin Hall angle, we find a dominant interface contribution to the ultrafast charge current whose magnitude amounts to as much as about 20% of that found in an F|Pt reference sample. Symmetry arguments and first-principles calculations strongly suggest that the interfacial S2C arises from skew scattering of spinpolarized electrons at interface imperfections. Our results highlight the potential of skew scattering for interfacial S2C and propose a promising route to enhanced S2C by tailored interfaces at all frequencies from DC to terahertz.
Original languageEnglish
Article number2006281
Number of pages9
JournalAdvanced Materials
Volume33
Issue number9
Early online date27 Jan 2021
DOIs
Publication statusPublished - 4 Mar 2021

Keywords

  • terahertz emission spectroscopy
  • spin-to-charge conversion
  • interface
  • skew scattering

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