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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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: Journal Article
Language:English
Published: 2023
Subjects:
Online Access:https://hdl.handle.net/10356/171271
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author Agarwal, Piyush
Yang, Yingshu
Medwal, Rohit
Asada, Hironori
Fukuma, Yasuhiro
Battiato, Marco
Singh, Ranjan
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Agarwal, Piyush
Yang, Yingshu
Medwal, Rohit
Asada, Hironori
Fukuma, Yasuhiro
Battiato, Marco
Singh, Ranjan
author_sort Agarwal, Piyush
collection NTU
description 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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spelling ntu-10356/1712712024-04-11T08:01:02Z Secondary spin current driven efficient THz spintronic emitters Agarwal, Piyush Yang, Yingshu Medwal, Rohit Asada, Hironori Fukuma, Yasuhiro Battiato, Marco Singh, Ranjan School of Physical and Mathematical Sciences The Photonics Institute Centre for Disruptive Photonic Technologies (CDPT) Physics Secondary Excitation Secondary Spin Currents 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. National Research Foundation (NRF) R.S. and P.A. would like to acknowledge the National Research Foundation, Singapore, for the support through NRF-CRP23-2019-0005. M.B. would like to acknowledge the NAP-SUG grant. 2023-10-18T02:54:41Z 2023-10-18T02:54:41Z 2023 Journal Article Agarwal, P., Yang, Y., Medwal, R., Asada, H., Fukuma, Y., Battiato, M. & Singh, R. (2023). Secondary spin current driven efficient THz spintronic emitters. Advanced Optical Materials. https://dx.doi.org/10.1002/adom.202301027 2195-1071 https://hdl.handle.net/10356/171271 10.1002/adom.202301027 2-s2.0-85168607949 en NRF-CRP23-2019-0005 Advanced Optical Materials 10.21979/N9/INJ449 © 2023 Wiley-VCH GmbH. All rights reserved.
spellingShingle Physics
Secondary Excitation
Secondary Spin Currents
Agarwal, Piyush
Yang, Yingshu
Medwal, Rohit
Asada, Hironori
Fukuma, Yasuhiro
Battiato, Marco
Singh, Ranjan
Secondary spin current driven efficient THz spintronic emitters
title Secondary spin current driven efficient THz spintronic emitters
title_full Secondary spin current driven efficient THz spintronic emitters
title_fullStr Secondary spin current driven efficient THz spintronic emitters
title_full_unstemmed Secondary spin current driven efficient THz spintronic emitters
title_short Secondary spin current driven efficient THz spintronic emitters
title_sort secondary spin current driven efficient thz spintronic emitters
topic Physics
Secondary Excitation
Secondary Spin Currents
url https://hdl.handle.net/10356/171271
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