Spontaneous spin and valley polarizations in a two-dimensional Cr2S3 monolayer.

Valleytronics has attracted much attention due to its potential applications in information progress and data storage. In this paper, monolayer Cr₂S₃ is proven to be a ferromagnetic (FM) semiconductor by using first-principles calculations. Moreover, monolayer Cr₂S₃ exhibits a perpendicular magnetic anisotropy energy of 30 μeV/f.u. Surprisingly, monolayer Cr₂S₃ presents spontaneous valley polarization, which means that it will be nonvolatile for data storage. Notably, monolayer Cr₂S₃ changes to an antiferromagnetic (AFM) state from the original FM state under biaxial tensile strain, and its easy axis will be reorientated from out-of-plane to in-plane when the compressive strain is larger than −2%. Importantly, for AFM monolayer Cr₂S₃, the valley polarization reversion can be realized by an external electric field along the z direction. In brief, valley polarization has been achieved in both FM and AFM monolayer Cr₂S₃, which is very rare in other valleytronics research. The present research provides a tantalizing candidate for realizing and manipulating valley and spin physics. [ABSTRACT FROM AUTHOR]