Contributed talk

Magnetic topological graphene nanoribbons
Shayan Edalatmanesh¹, S. Song², P. W. Ng², A. Pinar Sole¹, X. Peng², J. Kolorenc¹, Z. Sosnova¹, O. Stetsovych¹, J. Su², A. Liebig³, J. Wu², F Giessibl³, P. Jelinek¹, C. Chi² and J. Lu²

1 Institute of Physics of the Czech Academy of Science (Czech Republic)
2 Department Of Chemistry, National University of Singapore (Singapore)
3 Department of Physics, University of Regensburg (Germany)

The interplay of magnetism and topology lies at the heart of condensed matter physics, which offers great opportunities to design magnetic topological materials hosting a variety of exotic topological quantum states including the quantum anomalous Hall effect, axion insulator state, and Majorana bound states. Extending this concept to one-dimension (1D) systems offers additional rich quantum spin physics with great promise for molecular-scale spintronics.

In this presentation I will discuss the benefits of the application of the SSH model [1] and topological classification to more complex 1D π-conjugated systems (compared to polyacetylene chains). After a brief introduction I will present theoretical calculations and experimental measurements for a family of curved-like graphene nanoribbons (GNRs) with two distinct topological phases. The topological phase transition from trivial to nontrivial brings terminal magnetism (captured using a single-nickelocene spin sensor) and bandgap reopening to the GNRs, possibly suitable for bandgap engineering in future devices. Finally, I’ll discuss that the transition from strong anti-ferromagnetic to weak coupling (paramagnetism-like) between the terminal spins and its controllability via tuning the length of the GNRs.

[1] W. P. Su, et al. A. Phys. Rev. Lett. 42, 1698 (1979)