Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 70: Poster: Spins on Surfaces & Surface Magnetism
O 70.14: Poster
Mittwoch, 20. März 2024, 18:00–20:00, Poster C
Spin and charge control of topological end states in chiral graphene nanoribbons — •Leonard Edens1, Francisco Romero1, Manuel Vilas-Varela2, Giuliana Beretta3, Sofia Sanz4, Thomas Frederikssen4, Diego Peña2, and Nacho Pascual1 — 1CIC nanoGUNE, Spain — 2CiQUS and Universidade de Santiago de Compostela, Spain — 3Politecnico di Torino, Italy — 4DIPC, Spain
Chiral graphene nanoribbons can exhibit radical end states due to nontrivial electronic topology. A localized spin fingerprint however remains unobserved as electron transfer to or from the underlying catalyst metal due to work function mismatch causes deviation from half filling, quenching spin. Gold alloyed with rare-earth metals still catalyses on-surface synthesis while exhibiting a lower work function. We show here that (3,2,8)-chiral nanoribbons can be synthesized with atomic precision on the ferromagnetic GdAu2 intermetallic surface, and do not undergo significant charge transfer. By tunneling spectroscopy, we furthermore observe that the occupancy of the two topological end states can be reversibly switched from singly to doubly occupied by lateral manipulation of the nanoribbon across the substrate’s moiré lattice. In the doublet case, low-energy features are interpreted as Kondo-screened spin-flip excitations of the π-radical state acted upon by the Gd 4f-mediated exchange bias.
Keywords: Nanoribbons; 2D magnetism; Topological insulators; STM; Boundary states