Tuning Rashba spin textures in asymmetric Bi2O2Se monolayer for spintronic applications

The Rashba effect, originating from spin-orbit interaction and crystal asymmetry, enables electric-field control of electron spins, making materials with strong Rashba splitting near the Fermi level attractive for spintronics. Using first-principles calculations, we identify asymmetric Bi 2 O 2 Se monolayer as a semiconductor exhibiting large Rashba splitting. Its structure induces a work function difference (Δ φ ) of 3.25 eV, dipole moment of 0.32 D, and a small band gap of 0.30 eV. The conduction band shows Rashba energy E R = 33.6 meV and coupling constant α R = 10.56 eV Å with circular spin texture around the Γ point. The monolayer remains mechanically stable under ± 10% strain, while strain and electric fields (≤0.3 V/Å) reversibly tune polarization and Rashba splitting. A finite out-of-plane spin component ( S z ) emerges from anisotropic SOC, demonstrating experimentally feasible and controllable spin-texture modulation. Both E R and α R increase under tensile strain, highlighting Bi 2 O 2 Se’s potential for high-efficiency spin-field-effect transistors and advanced semiconductor spintronics.