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Dance of magnetism and light: Study finds nonreciprocal second harmonic generation disappears in 2D material
A research group recently discovered the disappearance of nonreciprocal second harmonic generation (SHG) in MnPSe₃ when integrated into a two-dimensional (2D) antiferromagnetic MnPSe₃/graphene heterojunction.
The research, in Nano Letters, highlights the role of interfacial magnon-plasmon coupling in this phenomenon.
2D van der Waals magnetic/non-magnetic heterojunctions hold significant promise for spintronic devices. Achieving these functionalities hinges on the interfacial proximity effect, a critical factor. However, detecting the proximity effect in 2D antiferromagnetic/non-magnetic heterojunctions presents considerable challenges, due to the small size and weak signals associated with these structures.
In this study, the team used a home-made SHG system to observe that the nonreciprocal SHG of MnPSe₃ disappeared when it was in contact with graphene, in contrast to the antiferromagnetic MnPSe₃ layer alone. This change indicates the presence of interfacial coupling interaction or proximity effect.
To explore this effect further, the researchers incorporated a hexagonal boron nitride (h-BN) layer between the MnPSe₃ and graphene to isolate the interfacial interaction. Their experiments revealed that the interfacial coupling extended over a long range (>40 nm), significantly surpassing the typical range of a few nanometers typically observed in proximity effects.
Moreover, the team found that the strength of this coupling weakened as the band gap of the underlayer material increased, providing a way to tune the nonlinear SHG response. Through symmetry analysis, first-principles calculations, and comparison with previous studies, the researchers concluded that the disappearance of the nonreciprocal SHG signal was due to the coupling between graphene' s surface plasmons and MnPSe₃' s magnons.
"This discovery paves the way for manipulating the nonlinear optical properties of 2D heterojunctions and developing multifunctional, tunable 2D layered nonlinear optical devices," said Prof. Sheng Zhigao.
The study was led by Prof. Sheng from the Hefei Institutes of Â鶹ÒùÔºical Science of the Chinese Academy of Science.
More information: Ziyun Wang et al, Suppressed Nonreciprocal Second-Harmonic Generation of Antiferromagnet MnPSe₃ in the MnPSe₃/Graphene Heterostructure Due to Interfacial Magnon–Plasmon Coupling, Nano Letters (2024).
Journal information: Nano Letters
Provided by Chinese Academy of Sciences
