Topological insulator metamaterial with giant circular photogalvanic effect
Topological insulator metamaterial with giant circular photogalvanic effect
One of the most notable manifestations of electronic properties of topological insulators is the dependence of the photocurrent direction on the helicity of circularly polarized optical excitation. The helicity-dependent photocurrents, underpinned by spin-momentum locking of surface Dirac electrons, are weak and easily overshadowed by bulk contributions. Here, we show that the chiral response can be enhanced by nanostructuring. The tight confinement of electromagnetic fields in the resonant nanostructure enhances the photoexcitation of spin-polarized surface states of topological insulator Bi
1.5Sb
0.5Te
1.8Se
1.2, leading to an 11-fold increase of the circular photogalvanic effect and a previously unobserved photocurrent dichroism (Ρcirc = 0.87) at room temperature. The control of spin transport in topological materials by structural design is a previously unrecognized ability of metamaterials that bridges the gap between nanophotonics and spin electronics, providing opportunities for developing polarization-sensitive photodetectors.
Sun, Xinxing
2264494f-f425-4d5c-94bf-eebc150f5796
Adamo, Giorgio
8c4da92b-f849-42d4-99c8-b0eb4ba1c73a
Eginligil, Mustafa
924cfd95-0524-4877-b684-7c6a338f6543
Krishnamoorthy, Harish N.S.
87456c53-9077-4ccf-80b9-44470ad845b9
Zheludev, Nikolai
32fb6af7-97e4-4d11-bca6-805745e40cc6
Soci, Cesare
6c86324e-2968-4e90-9436-4a92a4b26cec
March 2021
Sun, Xinxing
2264494f-f425-4d5c-94bf-eebc150f5796
Adamo, Giorgio
8c4da92b-f849-42d4-99c8-b0eb4ba1c73a
Eginligil, Mustafa
924cfd95-0524-4877-b684-7c6a338f6543
Krishnamoorthy, Harish N.S.
87456c53-9077-4ccf-80b9-44470ad845b9
Zheludev, Nikolai
32fb6af7-97e4-4d11-bca6-805745e40cc6
Soci, Cesare
6c86324e-2968-4e90-9436-4a92a4b26cec
Sun, Xinxing, Adamo, Giorgio, Eginligil, Mustafa, Krishnamoorthy, Harish N.S., Zheludev, Nikolai and Soci, Cesare
(2021)
Topological insulator metamaterial with giant circular photogalvanic effect.
Science Advances, 7 (14), [eabe5748].
(doi:10.1126/sciadv.abe5748).
Abstract
One of the most notable manifestations of electronic properties of topological insulators is the dependence of the photocurrent direction on the helicity of circularly polarized optical excitation. The helicity-dependent photocurrents, underpinned by spin-momentum locking of surface Dirac electrons, are weak and easily overshadowed by bulk contributions. Here, we show that the chiral response can be enhanced by nanostructuring. The tight confinement of electromagnetic fields in the resonant nanostructure enhances the photoexcitation of spin-polarized surface states of topological insulator Bi
1.5Sb
0.5Te
1.8Se
1.2, leading to an 11-fold increase of the circular photogalvanic effect and a previously unobserved photocurrent dichroism (Ρcirc = 0.87) at room temperature. The control of spin transport in topological materials by structural design is a previously unrecognized ability of metamaterials that bridges the gap between nanophotonics and spin electronics, providing opportunities for developing polarization-sensitive photodetectors.
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Sun-2021-SCA-Topological Insulator
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Published date: March 2021
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Funding Information:
We would like to acknowledge J. Song for insightful discussions on fundamental processes underlying HDPC in Dirac materials; A. Dubrovkin, G. Yuan, and S. Aljunid for technical consultations; and W. Lan for providing the BSTS crystal. Funding: This research was supported by the Singapore Ministry of Education [grant no. MOE2016-T3-1-006 (S)], the UK Engineering and Physical Sciences Research Council (grant no.: EP/M009122/1) and the Singapore National Research Foundation, Prime Minister?s Office, under its Quantum Engineering Programme (grant no.: QEP-P1). M.E. acknowledges the 100 Foreign Talents Project in Jiangsu Province (JSA2016003) and the National Natural Science Foundation of China (NSFC 11774170) for travel support. Author contributions: C.S., M.E., and G.A. conceived the original idea. X.S. developed experimental setup with initial assistance from M.E. and performed all HDPC measurements. G.A. and X.S. developed the device fabrication process (G.A. fabricated the metamaterials and X.S. fabricated the devices). G.A. performed the electromagnetic simulations. H.N.S.K. did ellipsometric measurements and extracted the optical constants. X.S., G.A., and C.S analyzed the data and drafted the manuscript. All authors contributed to the discussion and revision of the manuscript. C.S. and N.I.Z. supervised the work. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. The data that support the findings of this study are openly available in NTU research data repository DR-NTU (Data) at https://doi.org/10.21979/N9/U9UXXV. Additional data related to this paper may be requested from the authors.
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Copyright © 2021 The Authors, some rights reserved.
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Local EPrints ID: 449614
URI: http://eprints.soton.ac.uk/id/eprint/449614
ISSN: 2375-2548
PURE UUID: 491c5d49-e884-4242-ab6e-dcc22b6be841
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Date deposited: 09 Jun 2021 16:30
Last modified: 17 Mar 2024 02:39
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Contributors
Author:
Xinxing Sun
Author:
Giorgio Adamo
Author:
Mustafa Eginligil
Author:
Harish N.S. Krishnamoorthy
Author:
Cesare Soci
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