Electronic Transport Through Free-Standing Graphene Nanoribbons Using a Scanning Tunneling Microscope

CIC nanoGUNE Seminars

Speaker

Niklas Friedrich
Post-doctoral Researcher, Nanoimaging Group, CIC nanoGUNE

When

2023/06/26
11:00

Place

nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian

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Coherent electron transport through individual molecules is a vital technique to probe different quantum mechanical properties like energy level alignment, vibronic modes or spin states. Here, we investigate the electronic transport through on-surface synthesized graphene nanoribbons (GNRs) containing substitutionally embedded 2B-dimers by suspending individual GNRs in the junction between tip and substrate of a scanning tunnelling microscope (STM).

We show that embedding a single 2B-dimer inside a 7-armchair GNR induces a topological in-gap state and demonstrate its magnetic character [1]. We find that the coherent electron transport through the 2B-GNR is bipolar with the singly occupied in-gap state being responsible for resonant electron tunneling at either voltage polarity. The bipolar transport is favored due to the exponential localization of the 2B-state around the 2B-dimer that decouples the state electronically from both contacting electrodes and, therefore, creates a double tunneling barrier configuration. In transport experiments through ribbons with alternating width and periodic 2B-doping, we observe simultaneously length-independent conductance at zero bias, indicating a metallic band, and a stable Kondo resonance, unraveling its magnetic character [2].

References
[1] N Friedrich, P Brandimarte, et al., Phys. Rev. Lett., 125, 146801 (2020)
[2] N Friedrich, et al., ACS Nano, 16, 14819 (2022)