Abstract
We report on a giant Rashba type splitting of metallic bands observed in one-dimensional structures prepared on a vicinal silicon substrate. A single layer of Pb on Si(553) orders this vicinal surface making perfectly regular distribution of monatomic steps. Although there is only one layer of Pb, the system reveals very strong metallic and purely one-dimensional character, which manifests itself in multiple surface state bands crossing the Fermi level in the direction parallel to the step edges and a small band gap in the perpendicular direction. As shown by spin-polarized photoemission and density functional theory calculations these surface state bands are spin-polarized and completely decoupled from the rest of the system. The experimentally observed spin splitting of 0.6 eV at room temperature is the largest found to now in the silicon-based metallic nanostructures, which makes the considered system a promising candidate for application in spintronic devices.
Highlights
We report on a giant Rashba type splitting of metallic bands observed in one-dimensional structures prepared on a vicinal silicon substrate
In most cases the spin splitting is to small to be utilized in spintronic devices
According to density functional theory (DFT) calculations such giant spin splitting is caused by the unique arrangement of Pb atoms on each terrace of Institute of Physics, Maria Curie-Sklodowska University, Lublin, 20-031, Poland
Summary
The deposition of 1.3 ML Pb on Si(553) surface results in a Pb wetting layer which upon annealing makes the underneath Si surface ordered with perfectly regular distribution of monatomic steps. The corresponding calculations in the full unit cell geometry model of Si(553)-Pb show significant charge asymmetry in the plane of the surface, Fig. 6(b) This is the result of the nonuniform distribution of Pb atoms, and should lead to the appearance of a strong perpendicular component of the polarization as observed in other systems[23]. Apart from the appearance of the out-of-plane component of the polarization vector, the in-plane asymmetric charge distribution around nuclei of heavy atoms is known to strongly enhance the spin splitting of the surface bands[35] Such asymmetry of the charge distribution is already predicted for the full unit cell geometry model shown in Fig. 6(b) and support the giant spin splitting observed in the experiment. The spin-split surface bands are perfectly decoupled from the substrate assuring pure spin currents preventing their mixing with unpolarized substrate currents
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