Half-metal to magnetic semiconductor transition in Mn-doped monolayer Bi2O2Se tuned by strain

Recently, Bi₂O₂Se is discovered as a promising two-dimensional (2D) semiconductor for next generation electronics because of its stability in air, high Hall mobility and on/off ratio at room-temperature. Using first-principles calculations, we predict half-metallicity in Mn-doped monolayer Bi₂O₂Se. The magnetism enhancement from 4.0 to 6.0 µ_B and half-metal to magnetic semiconductor transition of monolayer Bi₂O₂Se are realizable by applying biaxial tensile strain. The symmetry reduction at the elastic-plastic transition is the key factor in controlling the magnetic coupling order between the Mn and the neighboring Se atoms. The results imply a possible way to achieve two-dimensional magnetic semiconductors that have great potential applications in spintronic devices.