Photocurrent Spectroscopy of Dark Magnetic Excitons in 2D Multiferroic NiI<sub>2</sub>
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 NiI<sub>2</sub>. 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 NiI<sub>2</sub>. In addition to probing the coupling between magnetic order and dark excitons, this work provides strong evidence for the multiferroicity of NiI<sub>2</sub> down to bilayer thickness, thus demonstrating the utility of photocurrent spectroscopy for revealing subtle opto-spintronic phenomena in the atomically thin limit.
Authors
- Luqing Wang (ORCID: https://orcid.org/0000-0003-4567-2831)
- Pierre Darancet
- Dmitry Lebedev (ORCID: https://orcid.org/0000-0002-1866-9234)
- Mark C. Hersam (ORCID: https://orcid.org/0000-0003-4120-1426)
- Maria K. Y. Chan (ORCID: https://orcid.org/0000-0003-0922-1363)
- Takashi Taniguchi (ORCID: https://orcid.org/0000-0002-1467-3105)
- Thomas W. Song
- J. Tyler Gish (ORCID: https://orcid.org/0000-0001-8429-5800)
- Nathaniel P. Stern (ORCID: https://orcid.org/0000-0002-8903-3516)
- Qunfei Zhou (ORCID: https://orcid.org/0000-0002-8499-1993)
- Ethan S. Garvey
- Kenji Watanabe (ORCID: https://orcid.org/0000-0001-6249-8666)
- Vinod K. Sangwan
Institutions
- Northwestern University (US)
- Argonne National Laboratory (US)
- National Institute for Materials Science (JP)
Publication Details
- Journal
- Advanced Science
- Published
- 2024-08-09
- DOI
- https://doi.org/10.1002/advs.202407862
- Citations
- 7
- Primary Topic
- 2D Materials and Applications
- Type
- article
- Field-Weighted Citation Impact
- 0.82
Funders
- National Science Foundation
- U.S. Department of Energy
- Northwestern University
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Materials Research Science and Engineering Center, Harvard University
- International Institute for Nanotechnology, Northwestern University
- Japan Society for the Promotion of Science
- Office of Naval Research
- Division of Materials Research
- Division of Electrical, Communications and Cyber Systems