Quasiparticle interference on the surface of Bi2Se3 terminated (PbSe)5(Bi2Se3)6

Among the family of topological superconductors derived from Bi2Se3, Cux(PbSe)5(Bi2Se3)6 is unique in its surface termination of a single quintuple layer (QL) of the topological insulator (TI) Bi2Se3 on an ordinary insulator PbSe. Here, we report a combined scanning tunneling microscopy (STM) and density functional theory (DFT) characterization of the cleaved surface of the parent compound (PbSe)5(Bi2Se3)6 (PSBS). Interestingly, the potential disorder due to the random distribution of native defects is only Γ ∼ 4 meV, among the smallest reported for TIs. Performing high-resolution quasiparticle interference imaging (QPI) near the Fermi energy (E−EF = −1 eV to 0.6 eV) we reconstruct the dispersion relation of the dominant spectral feature and our ab initio calculations show that this surface feature originates from two bands with Rashba-like splitting due to strong spin-orbit coupling and inversion symmetry breaking. Moreover, a small hexagonal distortion of the calculated Fermi surface is seen in the full momentum space distribution of the measured scattering data. Interestingly, the scattering pattern transforms into a flower-like shape with suppressed intensity along the ΓK direction, at lower energies. However, this change is not due to the forbidden backscattering in the topological surface state in Bi2Se3 but the threefold symmetry of the scattering potential itself.

This dataset contains the experimental and theoretical data of this work.