Spin-polarized surface states on Br/Ge(111)-(1×1): Surface spin polarization without heavy elements

Two-dimensional states localized in subsurface layers of Ge(111)

“…The surface states were found to have negligible contribution of surface * aruga@kuchem.kyoto-u.ac.jp Bi orbitals, thus the Rashba spin polarization was ascribed exclusively to the spin-orbit interaction (SOI) at the nuclei of Ge atoms. Similar subsurface states were also observed on Br/Ge(111)-(1×1) [7], Pb/Ge(111)-β-( 10], and Au/Ge(111)-( [11]. In this work, we report on the extensive analysis of the¯ electronic surface states around the bulk valence-band maximum (VBM) on Bi/Ge(111)-( √ 3 × √ 3)R30 • , Br/Ge(111)-(1×1), and Tl/Ge(111)-(1×1) by using density-functionaltheory (DFT) calculation and angle-resolved photoelectron spectroscopy (ARPES).…”

“…We have recently found novel surface states around thē point in the surface Brillouin zone (SBZ) on Ge(111) covered with foreign atoms, and showed that these surface states have characteristics typical of the perturbed-bulk-band type [6,7]. The spin polarization of these surface bands was first observed on Bi/Ge(111)-( √ 3 × √ 3)R30 • [6], which exhibited the Rashba-type spin polarization [8] characteristic of 2D surface states.…”

Experimental evidence for two-dimensional states localized in subsurface region of Ge(1 1 1)

“…We consider that a scenario of the formation of the subsurface states is common with the other systems such as Bi/Ge(1 1 1), Br/Ge(1 1 1), Tl/Ge(1 1 1) [11][12][13]. The subsurface states are yielded from the bulk electronic states perturbed by the truncation of bulk periodicity at the surface.…”

“…On the other hand, experimentally, details of the energy dispersion of the subsurface states remain unclear. For instance, it is difficult to identify the energy dispersion of light-hole-derived states as well as the spin splitting of heavy-hole-derived states [11,12]. We consider that low http://dx.doi.org/10.1016/j.elspec.2014.09.005 0368-2048/© 2014 Elsevier B.V. All rights reserved.…”

“…On the other hand, recently, a new type of spin-polarized surface states derived from Ge, a lighter element, was found on Bi/Ge(1 1 1), Br/Ge(1 1 1), Tl/Ge(1 1 1) and Pb/Ge(1 1 1), in which the surface states disperse near the valence band maximum (VBM) of Ge bulk bands [11][12][13][14][15]. An insight into the spin-polarized two-dimensional states has been provided by a density functional theory (DFT) calculation [13].…”