Abstract
Protected and spin-polarized transport channels are the hallmark of topological insulators, coming along with an intrinsic strong spin-orbit coupling. Here we identified such corresponding chiral states in epitaxially grown zigzag graphene nanoribbons (zz-GNRs), albeit with an extremely weak spin-orbit interaction. While the bulk of the monolayer zz-GNR is fully suspended across a SiC facet, the lower edge merges into the SiC(0001) substrate and reveals a surface state at the Fermi energy, which is extended along the edge and splits in energy toward the bulk. All of the spectroscopic details are precisely described within a tight binding model incorporating a Haldane term and strain effects. The concomitant breaking of time-reversal symmetry without the application of external magnetic fields is supported by ballistic transport revealing a conduction of G = e2/h.
| Original language | English |
|---|---|
| Pages (from-to) | 2876-2882 |
| Number of pages | 7 |
| Journal | Nano Letters |
| Volume | 21 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 14 Apr 2021 |
Bibliographical note
Funding Information:Financial support by the Deutsche Forschungsgemeinschaft (Sta315/9-1, Te386/12-1, and Te 386/13-1) is gratefully acknowledged. Calculations were largely performed within the PyBinding framework as written by Dean Moldovan. Raman measurements were performed by R.E.S. School in collaboration with N.d.V. This work is part of the research programme FLAG-ERA with project number 15FLAG01-2, which is (partly) financed by the Dutch Research Council (NWO). The TEM experiments were performed together with Ioannis Alexandrou from Thermo Fisher Scientific (Eindhoven, The Netherlands). The authors thank Ulrike Waizmann and Thomas Reindl for performing the e-beam lithography and reactive ion etching at the Nanostructuring Lab of the Max Planck Institute for Solid State Research. We also thank MAX IV for offering us commissioning beamtime.
Funding
Financial support by the Deutsche Forschungsgemeinschaft (Sta315/9-1, Te386/12-1, and Te 386/13-1) is gratefully acknowledged. Calculations were largely performed within the PyBinding framework as written by Dean Moldovan. Raman measurements were performed by R.E.S. School in collaboration with N.d.V. This work is part of the research programme FLAG-ERA with project number 15FLAG01-2, which is (partly) financed by the Dutch Research Council (NWO). The TEM experiments were performed together with Ioannis Alexandrou from Thermo Fisher Scientific (Eindhoven, The Netherlands). The authors thank Ulrike Waizmann and Thomas Reindl for performing the e-beam lithography and reactive ion etching at the Nanostructuring Lab of the Max Planck Institute for Solid State Research. We also thank MAX IV for offering us commissioning beamtime.
Keywords
- ballistic transport channel
- STM
- tight binding
- topological surface state
- zigzag graphene nanoribbons