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Purely one-dimensional bands with a giant spin-orbit splitting: Pb nanoribbons on Si(553) surface

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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.

No MeSH data available.


Calculated charge distribution around Pb atoms.Charge distribution (a) in the reduced unit cell geometry (with  = 3.37 Å) and (b) in the full unit cell geometry models of the Si(553)-Pb surface. A color code denotes charge density in electrons/bohr3 units. A side view (along ) of the reduced (c) and full (d) unit cell geometry models. The charge density is averaged over the whole unit cell along . The brown (light blue) circles denote Pb (Si) atoms.
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f6: Calculated charge distribution around Pb atoms.Charge distribution (a) in the reduced unit cell geometry (with  = 3.37 Å) and (b) in the full unit cell geometry models of the Si(553)-Pb surface. A color code denotes charge density in electrons/bohr3 units. A side view (along ) of the reduced (c) and full (d) unit cell geometry models. The charge density is averaged over the whole unit cell along . The brown (light blue) circles denote Pb (Si) atoms.

Mentions: The existence of the component of the polarization vector perpendicular to the surface can also be explained by an asymmetric charge distribution around Pb atoms, Fig. 6. In the case of the reduced unit cell geometry model the asymmetry in the charge distribution is very small, Fig. 6(a), thus the obtained out-of-plane component is small too. However, 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 systems23. Indeed, the experiment also gives the out-of-plane polarization component (Fig. 4) much larger than the one predicted by the reduced unit cell geometry model, Fig. 5(b,c). Similar calculations performed along the steps show quite significant asymmetry, too, Fig. S6. However, as the asymmetry in the charge distribution and the resulting electric field is parallel to the direction it could contribute to the out-of-plane component of the polarization vector only if the electron have moved in the perpendicular direction, i.e. .


Purely one-dimensional bands with a giant spin-orbit splitting: Pb nanoribbons on Si(553) surface
Calculated charge distribution around Pb atoms.Charge distribution (a) in the reduced unit cell geometry (with  = 3.37 Å) and (b) in the full unit cell geometry models of the Si(553)-Pb surface. A color code denotes charge density in electrons/bohr3 units. A side view (along ) of the reduced (c) and full (d) unit cell geometry models. The charge density is averaged over the whole unit cell along . The brown (light blue) circles denote Pb (Si) atoms.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382770&req=5

f6: Calculated charge distribution around Pb atoms.Charge distribution (a) in the reduced unit cell geometry (with  = 3.37 Å) and (b) in the full unit cell geometry models of the Si(553)-Pb surface. A color code denotes charge density in electrons/bohr3 units. A side view (along ) of the reduced (c) and full (d) unit cell geometry models. The charge density is averaged over the whole unit cell along . The brown (light blue) circles denote Pb (Si) atoms.
Mentions: The existence of the component of the polarization vector perpendicular to the surface can also be explained by an asymmetric charge distribution around Pb atoms, Fig. 6. In the case of the reduced unit cell geometry model the asymmetry in the charge distribution is very small, Fig. 6(a), thus the obtained out-of-plane component is small too. However, 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 systems23. Indeed, the experiment also gives the out-of-plane polarization component (Fig. 4) much larger than the one predicted by the reduced unit cell geometry model, Fig. 5(b,c). Similar calculations performed along the steps show quite significant asymmetry, too, Fig. S6. However, as the asymmetry in the charge distribution and the resulting electric field is parallel to the direction it could contribute to the out-of-plane component of the polarization vector only if the electron have moved in the perpendicular direction, i.e. .

View Article: PubMed Central - PubMed

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.

No MeSH data available.