Large Rashba spin splitting of a metallic surface-state band on a semiconductor surface

Abstract

The generation of spin-polarized electrons at room temperature is an essential step in developing semiconductor spintronic applications. To this end, we studied the electronic states of a Ge(111) surface, covered with a lead monolayer at a fractional coverage of 4/3, by angle-resolved photoelectron spectroscopy (ARPES), spin-resolved ARPES and first-principles electronic structure calculation. We demonstrate that a metallic surface-state band with a dominant Pb 6p character exhibits a large Rashba spin splitting of 200 meV and an effective mass of 0.028 me at the Fermi level. This finding provides a material basis for the novel field of spin transport/accumulation on semiconductor surfaces. Charge density analysis of the surface state indicated that large spin splitting was induced by asymmetric charge distribution in close proximity to the nuclei of Pb atoms.

Spin-flip transitions and departure from the Rashba model in the Au(111) surface

“…The family of bismuth alloy surfaces, 2,5,6 for instance, exhibits giant spin-orbit energy shifts of nearly 400 meV. Other interesting examples include the semiconducting surfaces Tl/Si(111)−(1 × 1), [7][8][9] Tl/Ge(111)−(1 × 1), 10 and Pb/Ge(111)−β √ 3 × √ 3R30 • , 11,12 among many others. In these systems, the bulk bands present a gap near the Fermi level, and thus the electron transport properties are strongly influenced by the spin-split metallic surface states.…”

Relativistic effects and fully spin-polarized Fermi surface at the Tl/Si(111) surface

“…13,14 On one hand, these types of surfaces have been recently found to exhibit exceptional relativistic effects, 15,16 inducing spin-orbit energy shifts two orders of magnitude bigger than those found at normal semiconductor heterojunctions. From the practical point of view, heavy elements such as Tl or Sb are widely used in electronic instruments such as infrared detectors 17 or Halleffect devices.…”

Fermi Nesting between Atomic Wires with Strong Spin-Orbit Coupling

“…Within this model the main contributions to the spin splitting are the Z of the material [7], the orbital mixing, and the atomic corrugation [10]. The high Z of Pb alone can not explain the observed magnitude as is clear from a comparison to the densely packed Pb monolayer on Ge(111) where α R = 0.24 eVÅ was found [29]. We are therefore left to conclude that the charge distribution is strongly altered by the wires and differs from the isotropic 2D case.…”