Professor Katsunori Wakabayashi's group reveal optically induced spin currents in Janus NbSSe monolayers

On 2025, the results of research by Professor Katsunori Wakabayashi of the School of Science and Technology, Kwansei Gakuin University, on optically induced spin currents in monolayer Janus NbSSe were published in the international scientific journal Physical Chemistry Chemical Physics.

Two-dimensional materials have attracted considerable attention because electrons in these atomically thin systems can exhibit unusual quantum properties. Among them, Janus transition-metal dichalcogenides are particularly interesting because their atomic structure is asymmetric: the top and bottom atomic layers are composed of different elements. This structural asymmetry produces strong spin–orbit coupling, which plays an important role in spin-related electronic phenomena.

In this study, the research group theoretically investigated the electronic structure and optical response of the Janus NbSSe monolayer using first-principles calculations. The results show that light irradiation can generate a pure spin current, in which the spin of electrons flows without accompanying charge transport. The study also demonstrates that the direction and characteristics of the spin current can be controlled by changing the polarization of the incident light.

These findings provide a new mechanism for controlling spin information using light and offer theoretical guidelines for designing next-generation opto-spintronics devices. Such technologies may contribute to future low-energy electronics and advanced information processing systems.

This work was supported by JSPS KAKENHI (Grants No. JP25K01609, No. JP22H05473, and No. JP21H01019), JST CREST(Grant No. JPMJCR19T1),  the financial support for Basic Science Research Projects (Grant No. 2401203) from the Sumitomo Foundation, and Kwansei Gakuin University 2025 Individual Special Research Grant.

Journal name: Physical Chemistry Chemical Physics
Article title: Optically induced spin Hall current in monolayer Janus NbSSe
Author(s): Souren Adhikary, Tomoaki Kameda, Katsunori Wakabayashi
DOI: 10.1039/D5CP02135A