Giant Rashba system on a semiconductor substrate with tunable Fermi level: Bi/GaSb(110)–(2×1)

We fabricated spin-polarized surface electronic states with tunable Fermi levels from a semiconductor to low-dimensional metal in the Bi/GaSb(110)-$(2\ifmmode\times\else\texttimes\fi{}1)$ surface using angle-resolved photoelectron spectroscopy (ARPES) and spin-resolved ARPES. The spin-polarized surface band of Bi/GaSb(110) exhibits quasi-one-dimensional character with the Rashba parameter ${\ensuremath{\alpha}}_{\mathrm{R}}$ of 4.1 and 2.6 eV\AA{} at the $\overline{\mathrm{\ensuremath{\Gamma}}}$ and $\overline{\mathrm{Y}}$ points of the surface Brillouin zone, respectively. The Fermi level of the surface electronic state is tuned in situ by element-selective Ar-ion sputtering on the GaSb substrate. The giant Rashba-type spin splitting with switchable metallic/semiconducting character on a semiconductor substrate makes this system a promising candidate for future research in low-dimensional spintronic phenomena.