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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 electronic structure of Si(553)-Pb.Contribution of different orbitals, denoted by a diameter of circles, to the band structure of Si(553)-Pb. Top row - Pb, bottom row - Si.
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f2: Calculated electronic structure of Si(553)-Pb.Contribution of different orbitals, denoted by a diameter of circles, to the band structure of Si(553)-Pb. Top row - Pb, bottom row - Si.

Mentions: According to the DFT calculations the band structure along the nanoribbons reveals six parabolic-like bands crossing the Fermi energy around the point of the surface Brillouin zone similarly as in the experiment, Fig. 2, (the corresponding bands are denoted as the thicker lines). It is important to note that the DFT calculations of the electronic structure have been performed within reduced unit cell geometry model, Fig. S1 of Supplementary Information and Methods section. Within that model the Pb atoms are uniformly distributed on the terrace and form an almost ideal hexagonal lattice with the unit cell of . In fact, the hexagonal lattice is strongly distorted and the distances between Pb atoms in the unit cell are not uniform and vary between 3.04 and 3.60 Å, Fig. S1 of Supplementary Information. Applying the full unit cell geometry model in the DFT calculations, which includes more than 300 atoms, gives a huge number of folded bands and makes obtained results useless. Thus, in the following, the calculated electronic structure is based on the reduced unit cell geometry model. Therefore, we do not expect a perfect agreement between the band structures obtained with DFT and ARPES. Nevertheless, such calculations should give some clues regarding the nature and origin of the measured electronic structure.


Purely one-dimensional bands with a giant spin-orbit splitting: Pb nanoribbons on Si(553) surface
Calculated electronic structure of Si(553)-Pb.Contribution of different orbitals, denoted by a diameter of circles, to the band structure of Si(553)-Pb. Top row - Pb, bottom row - Si.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Calculated electronic structure of Si(553)-Pb.Contribution of different orbitals, denoted by a diameter of circles, to the band structure of Si(553)-Pb. Top row - Pb, bottom row - Si.
Mentions: According to the DFT calculations the band structure along the nanoribbons reveals six parabolic-like bands crossing the Fermi energy around the point of the surface Brillouin zone similarly as in the experiment, Fig. 2, (the corresponding bands are denoted as the thicker lines). It is important to note that the DFT calculations of the electronic structure have been performed within reduced unit cell geometry model, Fig. S1 of Supplementary Information and Methods section. Within that model the Pb atoms are uniformly distributed on the terrace and form an almost ideal hexagonal lattice with the unit cell of . In fact, the hexagonal lattice is strongly distorted and the distances between Pb atoms in the unit cell are not uniform and vary between 3.04 and 3.60 Å, Fig. S1 of Supplementary Information. Applying the full unit cell geometry model in the DFT calculations, which includes more than 300 atoms, gives a huge number of folded bands and makes obtained results useless. Thus, in the following, the calculated electronic structure is based on the reduced unit cell geometry model. Therefore, we do not expect a perfect agreement between the band structures obtained with DFT and ARPES. Nevertheless, such calculations should give some clues regarding the nature and origin of the measured electronic structure.

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.