Home > Research > Publications & Outputs > THz emission from Co/Pt bilayers with varied ro...

Associated organisational unit

Electronic data

  • Li_PRMat_just_accepted

    Rights statement: © 2019 American Physical Society

    Accepted author manuscript, 2.59 MB, PDF document

    Available under license: CC BY-NC: Creative Commons Attribution-NonCommercial 4.0 International License

Links

Text available via DOI:

View graph of relations

THz emission from Co/Pt bilayers with varied roughness, crystal structure, and interface intermixing

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Published
Close
Article number084415
<mark>Journal publication date</mark>19/08/2019
<mark>Journal</mark>Physical Review Materials
Issue number8
Volume3
Number of pages11
Publication StatusPublished
<mark>Original language</mark>English

Abstract

Ultrafast demagnetization of Co/Pt heterostructures induced by a femtosecond 800-nm laser pulse launches a spin current from Co to Pt and subsequent conversion of the spin current to a charge current in the Pt layer due to the inverse spin-Hall effect. At the same time, due to the spin-dependent photogalvanic effect, a circularly polarized femtosecond laser pulse also generates a photocurrent at the Co/Pt interface. Both ultrashort photocurrent pulses are effectively detected in a contactless way by measuring the THz radiation they emit. Here we aim to understand how the properties of the Co/Pt interface affect the photocurrents in the bilayers. By varying the interfacial roughness, crystal structure, and interfacial intermixing, as well as having an explicit focus on the cases when THz emissions from these two photocurrents reveal opposite trends, we identify which interface properties play a crucial role for the photocurrents. In particular, we show that by reducing the roughness, the THz emission due to the spin-dependent photogalvanic effect reduces to zero while the strength of the THz emission from the photocurrent associated with the inverse spin-Hall effect increases by a factor of 2. On the other hand, while intermixing strongly enhances the THz emission from the inverse spin-Hall effect by a factor of 4.2, THz emission related to the spin-dependent photogalvanic effect reveals the opposite trend. These findings indicate that microstructural properties of the Co-Pt interface play a decisive role in the generation of photocurrents.

Bibliographic note

© 2019 American Physical Society