| 1. |
- Aristov, Victor Yu., et al.
(författare)
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Graphene Synthesis on Cubic SiC/Si Wafers. Perspectives for Mass Production of Graphene-Based Electronic Devices
- 2010
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:3, s. 992-995
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Tidskriftsartikel (refereegranskat)abstract
- The outstanding properties of graphene, a single graphite layer, render it a top candidate for substituting silicon in future electronic devices, The so far exploited synthesis approaches, however, require conditions typically achieved in specialized laboratories and result in graphene sheets whose electronic properties are often altered by interactions with substrate materials. The development of graphene-based technologies requires an economical fabrication method compatible with mass production. Here we demonstrate for the fist Lime the feasibility of graphene synthesis on commercially available cubic SiC/Si substrates of >300 mm in diameter, which result in graphene flakes electronically decoupled from the substrate. After optimization of the preparation procedure, the proposed synthesis method can represent a further big step toward graphene-based electronic technologies.
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| 2. |
- Heckmann, Olivier, et al.
(författare)
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Quasi 1D Structures at the Bi/InAs(100) Surface
- 2018
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Ingår i: APPLIED PHYSICS OF CONDENSED MATTER (APCOM 2018). - : AMER INST PHYSICS. - 9780735417120
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Konferensbidrag (refereegranskat)abstract
- Thin Bi films are interesting candidates for spintronic applications due to a large spin-orbit splitting that, combined with the loss of inversion symmetry at the surface, results in a band structure that is not spin-degenerate. In recent years, applications for topological insulators based on Bi and Bi alloys have as well attracted much attention. Here we present angle-resolved photoemission spectroscopy studies of the Bi/InAs(100) interface. Bismuth deposition followed by annealing of the surface results in the formation of one full Bi monolayer decorated by Bi nanolines. We found that the building up of the interface does not affect the electronic structure of the substrate. As a consequence of weak interaction, Bi states are placed in the gaps of the electronic structure of InAs(100). We observe a strong resonance of the Bi electronic states close to the Fermi level; its intensity depends on the photon energy and the photon polarization. These states show nearly no dispersion when measured perpendicular to the nanolines, confirming their one-dimensionality.
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| 3. |
- Krieger, Jonas A., et al.
(författare)
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Weyl spin-momentum locking in a chiral topological semimetal
- 2024
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Ingår i: Nature Communications. - 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Spin-orbit coupling in noncentrosymmetric crystals leads to spin-momentum locking – a directional relationship between an electron’s spin angular momentum and its linear momentum. Isotropic orthogonal Rashba spin-momentum locking has been studied for decades, while its counterpart, isotropic parallel Weyl spin-momentum locking has remained elusive in experiments. Theory predicts that Weyl spin-momentum locking can only be realized in structurally chiral cubic crystals in the vicinity of Kramers-Weyl or multifold fermions. Here, we use spin- and angle-resolved photoemission spectroscopy to evidence Weyl spin-momentum locking of multifold fermions in the chiral topological semimetal PtGa. We find that the electron spin of the Fermi arc surface states is orthogonal to their Fermi surface contour for momenta close to the projection of the bulk multifold fermion at the Γ point, which is consistent with Weyl spin-momentum locking of the latter. The direct measurement of the bulk spin texture of the multifold fermion at the R point also displays Weyl spin-momentum locking. The discovery of Weyl spin-momentum locking may lead to energy-efficient memory devices and Josephson diodes based on chiral topological semimetals.
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| 4. |
- Nafday, Dhani, et al.
(författare)
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Electronic structure of Bi nanolines on InAs(100)
- 2023
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 611
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Tidskriftsartikel (refereegranskat)abstract
- Self-assembled nanolines are attractive to build the technological devices of next generation, but characterizing their electronic properties is often difficult to achieve. In this work we employ angle-resolved photoemission spectroscopy and density functional theory to clarify the electronic structure exhibited by self-assembled Bi nanolines grown on the InAs(100) surface. A surface resonance associated to the reconstructed ζ(4 × 2) surface is visible in the photoemission spectra before and after the formation of the Bi nanolines. This demonstrates that Bi deposition does not necessarily drive a transition to an unreconstructed surface in the substrate, which is contrary to what was reported in previous studies. In addition, experiment and theory show the presence of a flat band located in the band gap of InAs, just above the valence band maximum. This flat band is associated to the Bi nanolines and possesses a strong orbital character, consistent with its unidimensional nature. These spectral features suggest that Bi nanolines on InAs(100) may have a strongly polarized conductivity, which makes them suitable to be exploited as nanowires in nanotechnology. The coexistence with an accumulation layer suggests an even farther functionalization.
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