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arXiv · 1912.12094

Probing the magnetism of topological end-states in 5-armchair graphene nanoribbons

James Lawrence·Pedro Brandimarte·Alejandro Berdonces·Mohammed S. G. Mohammed·Abhishek Grewal·Christopher C. Leon·Daniel Sanchez-Portal·Dimas G. de Oteyza
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Abstract

We extensively characterize the electronic structure of ultra-narrow graphene nanoribbons (GNRs) with armchair edges and zig-zag termini that have 5 carbon atoms across their width (5-AGNRs), as synthesised on Au(111). Scanning tunnelling spectroscopy measurements on the ribbons, recorded on both the metallic substrate and a decoupling NaCl layer, show well-defined dispersive bands and in-gap states. In combination with theoretical calculations, we show how these in-gap states are topological in nature and localised at the zig-zag termini of the nanoribbons. Besides rationalising the driving force behind the topological class selection of 5-AGNRs, we also uncover the length-dependent behaviour of these end states which transition from singly occupied spin-split states to a closed-shell form as the ribbons become shorter. Finally, we demonstrate the magnetic character of the end states via transport experiments in a model two-terminal device structure in which the ribbons are suspended between the scanning probe and the substrate that both act as leads.

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James Lawrence, Pedro Brandimarte, Alejandro Berdonces, Mohammed S. G. Mohammed, Abhishek Grewal, Christopher C. Leon, Daniel Sanchez-Portal, Dimas G. de Oteyza. 2020-01-07. Probing the magnetism of topological end-states in 5-armchair graphene nanoribbons. https://doi.org/10.1021/acsnano.9b10191

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