Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 18: Poster Monday: 2D Materials 1

O 18.13: Poster

Monday, September 5, 2022, 18:00–20:00, P4

Strongly correlated boundary states in topologically insulating chiral graphene nanoribbons tuned by contact potential — •Leonard Edens¹, Francisco Romero¹, Sofia Sanz², Amelia Domínguez-Celorrio⁵, Manuel Vilas-Varela³, Jingcheng Li⁴, David Serrate⁵, Diego Peña³, and Nacho Pascual^1,2 — ¹CIC nanoGUNE BRTA, San Sebastián, Spain — ²DIPC, San Sebastián, Spain — ³CIQUS and Departamento de Química Orgánica, Univ. de Santiago de Compostela, Spain — ⁴School of Physics, Sun Yat-sen University, Guangzhou, China — ⁵INMA, and Univ. de Zaragoza, 50009 Spain

Chiral graphene nanoribbons present a special class of nanographenes in that their distinct edge symmetry causes a topologically nontrivial band dispersion. Truncating such a ribbon results in a pair of symmetry-protected topological end states predicted to be spin-polarized. Metal substrates interact with the molecular orbitals, transferring charge and screening electron-electron correlations. We decouple the nanoribbons by dragging them onto an ultrathin large bandgap insulator using an STM, and also synthesize them on a low-work function surface. Scanning tunneling spectroscopy on the surface intermetallic GdAu2 reveals a near-neutral ribbon, showing its end state spin-split. On MgO/Ag(001), the ribbons are highly decoupled, leading a greatly enhanced tunneling lifetime, vibronic sidebands, a negative charge and an enhanced correlation gap of opening far in the quantized conduction band.