Electronic properties of α-Sn(100)2×1: Evidence for asymmetric dimer reconstruction

A well-ordered thick layer of α-Sn(100) has been grown on InSb(100). The low energy electron diffraction pattern showed a sharp 2×1 double domain reconstruction with very low background at room temperature. The electronic properties have been studied by core-level- and angle-resolved photoemission spectroscopy (ARPES). ARPES spectra showed the presence of a surface state at normal emission, 1.15 eV below the Fermi level. This state disperses downward 1.3 eV along the [010] direction. Core-level spectra are well fitted with three surface-shifted components at binding energies +0.22, −0.23, and −0.49 eV with respect to the bulk component. Such results are in agreement with theoretical calculations based on asymmetric dimers by [Z.-Y. Lu, G. Chiarotti, S. Scandolo, and E. Tosatti, Phys. Rev. B 58, 13698 (1998)], taking into account final state effects, and exclude the existence of symmetric dimers.