Photocurrent Spectroscopy of Dark Magnetic Excitons in 2D Multiferroic NiI2

Dmitry Lebedev; J. Tyler Gish; Ethan S. Garvey; Thomas W. Song; Qunfei Zhou; Luqing Wang; Kenji Watanabe; Takashi Taniguchi; Maria K Chan; Pierre Thomas Darancet; Nathaniel P. Stern; Vinod K. Sangwan; Mark C. Hersam

doi:10.1002/advs.202407862

Photocurrent Spectroscopy of Dark Magnetic Excitons in 2D Multiferroic NiI₂

Dmitry Lebedev, J. Tyler Gish, Ethan S. Garvey, Thomas W. Song, Qunfei Zhou, Luqing Wang, Kenji Watanabe, Takashi Taniguchi, Maria K Chan, Pierre Thomas Darancet, Nathaniel P. Stern, Vinod K. Sangwan^*, Mark C. Hersam^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

Two-dimensional (2D) antiferromagnetic (AFM) semiconductors are promising components of opto-spintronic devices due to terahertz operation frequencies and minimal interactions with stray fields. However, the lack of net magnetization significantly limits the number of experimental techniques available to study the relationship between magnetic order and semiconducting properties. Here, they demonstrate conditions under which photocurrent spectroscopy can be employed to study many-body magnetic excitons in the 2D AFM semiconductor NiI₂. The use of photocurrent spectroscopy enables the detection of optically dark magnetic excitons down to bilayer thickness, revealing a high degree of linear polarization that is coupled to the underlying helical AFM order of NiI₂. In addition to probing the coupling between magnetic order and dark excitons, this work provides strong evidence for the multiferroicity of NiI₂ down to bilayer thickness, thus demonstrating the utility of photocurrent spectroscopy for revealing subtle opto-spintronic phenomena in the atomically thin limit.

Original language	English (US)
Article number	2407862
Journal	Advanced Science
Volume	11
Issue number	38
DOIs	https://doi.org/10.1002/advs.202407862
State	Published - Oct 16 2024

Funding

This research was primarily supported by the National Science Foundation Division of Materials Research (NSF DMR\u20102004420). In addition, D.L. acknowledges support from the Swiss National Science Foundation for an Early PostDoc Mobility Fellowship (P2EZP2_181614) and the Materials Research Science and Engineering Center of Northwestern University (NSF DMR\u20102308691) for charge transport measurements. J.T.G. acknowledges support from the Department of Energy (DOE DE\u2010SC0019356) for device fabrication, and E.S.G. acknowledges support from the National Science Foundation Division of Materials Research (NSF DMR\u20101905986) for variable\u2010temperature cryostat measurements. K.W. and T.T. acknowledge support from JSPS KAKENHI (Grant Numbers 19H05790, 20H00354 and 21H05233) for hBN synthesis. This work made use of the Northwestern University NUANCE Center and the Northwestern University Micro/Nano Fabrication Facility (NUFAB), which have received support from the SHyNE Resource (NSF ECCS\u20101542205), the International Institute for Nanotechnology, and the Northwestern University MRSEC program (NSF DMR\u20102308691). The Lakeshore CRX\u2010VF probe station, SuperK Extreme EXR\u201020 laser (NKT Photonics), and 2D crystal manipulation system (Graphene Industries) used in this work were supported by an Office of Naval Research DURIP Grant (ONR N00014\u201019\u20101\u20102297). This research was primarily supported by the National Science Foundation Division of Materials Research (NSF DMR-2004420). In addition, D.L. acknowledges support from the Swiss National Science Foundation for an Early PostDoc Mobility Fellowship (P2EZP2_181614) and the Materials Research Science and Engineering Center of Northwestern University (NSF DMR-2308691) for charge transport measurements. J.T.G. acknowledges support from the Department of Energy (DOE DE-SC0019356) for device fabrication, and E.S.G. acknowledges support from the National Science Foundation Division of Materials Research (NSF DMR-1905986) for variable-temperature cryostat measurements. K.W. and T.T. acknowledge support from JSPS KAKENHI (Grant Numbers 19H05790, 20H00354 and 21H05233) for hBN synthesis. This work made use of the Northwestern University NUANCE Center and the Northwestern University Micro/Nano Fabrication Facility (NUFAB), which have received support from the SHyNE Resource (NSF ECCS-1542205), the International Institute for Nanotechnology, and the Northwestern University MRSEC program (NSF DMR-2308691). The Lakeshore CRX-VF probe station, SuperK Extreme EXR-20 laser (NKT Photonics), and 2D crystal manipulation system (Graphene Industries) used in this work were supported by an Office of Naval Research DURIP Grant (ONR N00014-19-1-2297).

Keywords

2D materials
antiferromagnetism
dark exciton
multiferroicity
photocurrent

ASJC Scopus subject areas

Medicine (miscellaneous)
General Chemical Engineering
General Materials Science
Biochemistry, Genetics and Molecular Biology (miscellaneous)
General Engineering
General Physics and Astronomy

Access to Document

10.1002/advs.202407862

Cite this

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title = "Photocurrent Spectroscopy of Dark Magnetic Excitons in 2D Multiferroic NiI2",

abstract = "Two-dimensional (2D) antiferromagnetic (AFM) semiconductors are promising components of opto-spintronic devices due to terahertz operation frequencies and minimal interactions with stray fields. However, the lack of net magnetization significantly limits the number of experimental techniques available to study the relationship between magnetic order and semiconducting properties. Here, they demonstrate conditions under which photocurrent spectroscopy can be employed to study many-body magnetic excitons in the 2D AFM semiconductor NiI2. The use of photocurrent spectroscopy enables the detection of optically dark magnetic excitons down to bilayer thickness, revealing a high degree of linear polarization that is coupled to the underlying helical AFM order of NiI2. In addition to probing the coupling between magnetic order and dark excitons, this work provides strong evidence for the multiferroicity of NiI2 down to bilayer thickness, thus demonstrating the utility of photocurrent spectroscopy for revealing subtle opto-spintronic phenomena in the atomically thin limit.",

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author = "Dmitry Lebedev and Gish, {J. Tyler} and Garvey, {Ethan S.} and Song, {Thomas W.} and Qunfei Zhou and Luqing Wang and Kenji Watanabe and Takashi Taniguchi and Chan, {Maria K} and Darancet, {Pierre Thomas} and Stern, {Nathaniel P.} and Sangwan, {Vinod K.} and Hersam, {Mark C.}",

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AU - Wang, Luqing

AU - Watanabe, Kenji

AU - Taniguchi, Takashi

AU - Chan, Maria K

AU - Darancet, Pierre Thomas

AU - Stern, Nathaniel P.

AU - Sangwan, Vinod K.

AU - Hersam, Mark C.

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