  One-dimensional (1D) electronic states were discovered on 1D surface atomic
structure of Bi fabricated on semiconductor InSb(001) substrates by
angle-resolved photoelectron spectroscopy (ARPES). The 1D state showed steep,
Dirac-cone-like dispersion along the 1D atomic structure with a finite direct
bandgap opening as large as 150 meV. Moreover, spin-resolved ARPES revealed the
spin polarization of the 1D unoccupied states as well as that of the occupied
states, the orientation of which inverted depending on the wave vector
direction parallel to the 1D array on the surface. These results reveal that a
spin-polarized quasi-1D carrier was realized on the surface of 1D Bi with
highly efficient backscattering suppression, showing promise for use in future
spintronic and energy-saving devices.
