Contributed talk

Haiku graphene nanoribbons with tunable topology
Rodrigo E. Menchón¹, Pedro Brandimarte¹, Daniel Sánchez-Portal^1,2 and Aran Garcia-Lekue^1,3

1 Donostia International Physics Center (DIPC), 20018 Donostia, Spain 2 Centro de Física de Materiales CSIC-UPV/EHU, 20018 Donostia, Spain 3 Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain

Recent advances on surface-assisted synthesis open the door to engineering topological phases in atomically precise graphene nanoribbons (GNRs). However, to fully exploit their potential, a rational design is needed to achieve GNRs with optimal properties for spintronics or quantum computing applications.

Here we explore a novel family of armchair GNRs, which we name haiku-AGNRs, consisting of 5- and 7-atom wide segments. Based on ab initio simulations, we predict a tunable topological phase dependent on the density of the 7-atom wide segments, with the concomitant emergence or quenching of topological end and interface states [1]. Moreover, we derive a generalized Su-Schrieffer-Heeger (SSH) model that allows to treat haiku-AGNRs of technologically relevant lengths, thus providing valuable information for the devise of future experiments. Finally, we also present some results for B-doped periodic haiku-AGNRs in comparison with experiments performed at Prof. Pascual’s lab in nanoGUNE, San Sebastian (Spain) [2].

Figure 1: a) DFT-SIESTA band gap of 7-(5-AGNR)_nuc as a function of the density (1/nuc) of 7 widenings for periodic haiku ribbons with supercells containing nuc 5-AGNR unit cells. The band gap closes separating the topological and the trivial phases. The inset highlights the presence of a defect level localized around isolated 7-widenings for very dilute systems. Notice that the labels 575-AGNR and 7-(5-AGNR)₃ denote the same system. b) Spin polarized end states appearing at the boundaries of the 5-AGNR portion of a mixed 5-AGNR/575-AGNR long ribbon.

[1] R. E. Menchón, P. Brandimarte, D. Sánchez-Portal, and A. Garcia-Lekue, submitted 2023
[2] N. Friedrich, R. E Menchón, I. Pozo, J. Hieulle, A. Vegliante, J. Li, D. Sánchez-Portal, D. Peña, A. Garcia-Lekue and J. I. Pascual, ACS Nano 16, 14819-14826 (2022)