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TT: Fachverband Tiefe Temperaturen
TT 47: Fluctuations, Noise and Other Transport Topics (joint session TT/DY)
TT 47.9: Vortrag
Donnerstag, 20. März 2025, 17:15–17:30, H31
Dynamical current as tool to distinghuish degenerate spin states in open-shell graphene nanoribbons — •Nico Leumer, Thomas Frederiksen, and Geza Giedke — Donostia International Physics Center
The recent advances of surface synthesis unlocked the potential of open-shell physics in graphene nanoribbons (GNRs) which ever since have gained significant attention. Normally chemically unstable, these structures feature unpaired, localized pz-electrons pinned at zero energy, giving rise to the unique phenomenon of π-magnetism. Intrinsically low spin-orbit/hyperfine interactions suppress spin relaxation, making GNRs ideal for tunable spin physics and spintronics applications. Although scanning probe techniques provide the necessary access to electron’s spins and their interactions, state preparation, manipulation and detection remains an open challenge. Our ambition addresses the latter.
At half-filling certain GNRs host quasi degenerate spin singlets/triplets states with a vanishing energy gap for long ribbons. Without significantly increasing the gap, e.g., via magnetic fields, conventional current-based measurements hardly distinguish these spin textures. However, and even for absent gap, we demonstrate that in our setup I(t) discriminates between the responsible states by exploiting the states’s distinct spatial profiles. To probe the spatial information, we apply a constant bias between two STM tips. The scheme is suitable for single shot measurements and a quantum master equation (Hubbard model) accounts for the time evolution (GNR).
Keywords: Open-shell graphene nanoribbons; Half-filling singlet/triplet distinction