Giant Rashba Spin Splitting in Sb/Bi2Se3/Sb and Sb/Sb2Te3 /Sb Heterojunctions

Exploring semiconductor materials with huge Rashba spin splitting is of great significance for spintronic devices without a magnetic field. In this work, the structural and electronic properties of Sb/Bi2Se3/Sb (001) and Sb/Sb2Te3/Sb (001) heterojunctions were studied by first-principles calculations. Four different stacking heterojunctions with very small lattice mismatch were studied, and it was found that all of the heterojunctions were semiconductors with a band gap in the range of 0.05–0.2 eV. Interestingly, giant Rashba-type splitting (up to 5.2 eVÅ) near the Fermi level was induced in these heterojunctions due to the breaking of spatial inversion symmetry. Rashba splitting is mainly influenced by the pz orbital of Sb atoms, and the direction of the spin vectors near the Fermi level are all perpendicular to their momentum, and form two circles with opposite chirality. Because of the successful fabrication of Sb, Bi2Se3 and Sb2Te3, our discoveries provide promising candidates for overcoming the problems of small splitting and metallic Fermi surface in the current research of Rashba splitting for practical applications in spintronic devices.