Abstract
Janus monolayer materials, as the thinnest materials that may possess strong Rashba spin-orbit coupling, are helpful for the miniaturization of the charge-spin conversion devices. Using first-principles calculations, we investigated the structural stability and Rashba spin-orbit coupling of distorted Janus monolayer WSSe. Although the W atoms rotating around the Se atom are dynamically unstable in the stress-free state, the imaginary frequency disappears by applying a small compressive strain. From the perspectives of macroscopic charge transfer and microscopic atomic orbital compositions, the mechanism of the Rashba spin-orbit coupling strength of the distorted Janus monolayer WSSe was analyzed. The coupling strength can be greatly manipulated when −5 to 5% biaxial strain is applied. The charge transfer caused by the larger lattice constant and the rotation of the W atoms reduce the gradient of the potential so that the greater the electric polarization, the weaker the spin-orbit coupling. The coupling strength of different electronic states is determined by the proportion of the out-of-plane atomic orbitals, where and orbits play the dominant role. These results contribute to the design of materials with greater Rashba spin-orbit coupling and the understanding of its mechanism.
- Received 9 February 2021
- Revised 19 March 2021
- Accepted 22 March 2021
DOI:https://doi.org/10.1103/PhysRevB.103.195114
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