Secondary spin current driven efficient THz spintronic emitters

Secondary spin current driven efficient THz spintronic emitters

Femtosecond laser-induced photoexcitation of ferromagnet (FM)/heavy metal (HM) heterostructures has attracted attention by emitting broadband terahertz frequencies. The phenomenon relies on the formation of an ultrafast spin current, which is primarily attributed to the direct photoexcitation of the...

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Bibliographic Details
Main Authors: Agarwal, Piyush, Yang, Yingshu, Medwal, Rohit, Asada, Hironori, Fukuma, Yasuhiro, Battiato, Marco, Singh, Ranjan
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2023
Subjects:
Physics
Secondary Excitation
Secondary Spin Currents
Online Access:https://hdl.handle.net/10356/171271
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Institution: Nanyang Technological University
Language: English
Description
Summary:Femtosecond laser-induced photoexcitation of ferromagnet (FM)/heavy metal (HM) heterostructures has attracted attention by emitting broadband terahertz frequencies. The phenomenon relies on the formation of an ultrafast spin current, which is primarily attributed to the direct photoexcitation of the FM layer. However, during the process, the FM layer also experiences a secondary excitation led by the hot electrons from the HM layer that travel across the FM/HM interface and transfer additional energy in the FM. Thus, the generated secondary spins enhance the total spin current formation and lead to amplified spintronic terahertz emission. These results emphasize the significance of the secondary spin current, which even exceeds the primary spin currents when FM/HM heterostructures with thicker HM are used. An analytical model is developed to provide deeper insights into the microscopic processes within the individual layers, underlining the generalized ultrafast superdiffusive spin-transport mechanism.

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