Visible plasmons in ultra-corrugated graphene

Thermal cycling of graphene, supported on SiO2, leads to an increase in the corrugation aspect ratio of a factor of 3 or more. Plasmons are confined in ultra-corrugated graphene, leading to an increase in their frequency from the terahertz into the visible range.

In a research effort led by Levente Tapasztó (head of the Nanostructure Lab at EK), we show that the frequency of collective electron excitations (plasmons) in graphene can be increased significantly in highly corrugated graphene. The increase is caused by the confinement of graphene plasmons within the corrugations. The fact that the plasmon resonances shift from the terahertz range into the visible domain means that the coupling of light to the relativistic, Dirac charge carriers of graphene is much easier.

Our work in the Lendület group involved demonstrating, via quantum interference measurements, that the visible plasmons can also propagate through the sample. We’ve done this by coupling the tip of a scanning near field optical microscope (SNOM) to the propagating modes. These results have wide ranging consequences for the manipulation and tuning of graphene plasmons, as well as making possible extremely sensitive detectors for certain molecular species.

For more details, see our paper published in Nature Nanotechnology.

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