Regensburg 2019 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 16: Graphene II: Excitations and Nanoribbons (joint session O/TT)
TT 16.3: Talk
Monday, April 1, 2019, 15:30–15:45, H24
Molecular Spin Excitation by Electron Injection Through a Single Graphene Nanoribbon — •Niklas Friedrich1, Jingcheng Li1, Néstor Merino-Díez1,2, Dimas G. de Oteyza2, Diego Peña3, David Jacob4,5, and Nacho Pascual1,5 — 1CIC nanoGUNE, San Sebastian (Spain) — 2DIPC, San Sebastian (Spain) — 3CIQUS, Santiago de Compostela (Spain) — 4Departamento de Física de Materiales, UPV/EHU, San Sebastian (Spain) — 5Ikerbasque, Basque Foundation for Science, Bilbao (Spain)
Graphene nanoribbons (GNRs) and GNR-hybrids can be synthesized on metal surfaces with atomic precision using on surface synthesis techniques. Previously, we constructed a system in which chiral (3,1)-GNRs act as leads contacting a magnetic porphyrin molecule on a Au(111) substrate. Characterizing the porphyrin's magnetic properties by inelastic electron tunneling spectroscopy (IETS) we showed that the porphyrin's spin survives up to 4 contacting GNRs.
As a further step towards fully functional molecular devices, we now characterize the transport properties of linear GNR-porphyrin-GNR systems. We created a transport junction by contacting the system at a GNR end with the STM tip and lifting the molecular complex partially from the surface. We investigate the porphyrin's spin state via IETS by electrons cotunneling through the semiconducting GNR. In this transport configuration inelastic tunneling excites the Fe spin with excitation energies similar to the one measured by STS on surface. However, some molecular structures were found to lie in a mixed-valence state that vanished as the porphyrin was lifted from the metal.