An electrically switchable anti-ferroelectric bilayer In₂Se₃ based opto-spintronic device

Based on non-equilibrium Green's function combined with density functional theory (NEGF-DFT), we theoretically investigate the spin-related photogalvanic effect (PGE) in two anti-ferroelectric bilayer In₂Se₃ structures by atomic first-principles calculations. It is found that, due to the absence of inversion symmetry and the presence of strong spin-orbital interaction (SOI) in anti-ferroelectric bilayer In₂Se₃, the photoinduced charge-to-spin conversion can be achieved via the PGE. The generated spin-dependent photocurrent is largely spin-polarized and the corresponding spin polarization can vary from 0% to 100% depending on the photon energies, polarization and incident angles. Furthermore, it is found that, by tuning the polarization and the incident angles of light, the fully spin-polarized and pure spin photocurrent can be obtained. Most importantly, the spin dependent photocurrent can be largely tuned through the transition between two anti-ferroelectric bilayer In₂Se₃ states by the gate voltage. The defined relative spin dependent photoresponse change ratio n_s between two states is extremely large and its maximum value can be in the order of ∼10⁴. Therefore, our work demonstrates the great potential of bilayer In₂Se₃'s novel application in two-dimensional non-volatile opto-spintronic devices.