Jul 7, 2014
Double-slit experiment with twisted bilayer graphene
Young’s double-slit experiment played a pivotal role in the development of classical, as well as quantum, physics. It proved the wave nature of light, while its modern version using electron beams provides a solid foundation for quantum mechanics. It also stimulated long debates over the paradoxical structure and philosophical implications of quantum mechanics. Today, interference and diffraction are routine phenomena observed in material structure characterizations using X-ray or electron beams. Reporting in Nanotechnology, researchers from the University of Houston now observe a similar quantum interference effect in Raman scattering in twisted bilayer graphene.
When an excitation laser beam moves from a single-layer region to a bilayer region of twisted bilayer graphene islands the Raman intensity of the G line doubles. In contrast, the Raman intensity of the 2D band becomes about four times as strong. The four-fold enhancement of the 2D Raman band is a direct manifestation of the constructive interference between two Raman paths. The intensity of the G line represents an excellent example where there is no interference between two Raman paths.
There is a striking difference in the Raman spectra between twisted bilayer graphene and conventional AB-stacking bilayer graphene. In particular between the G line and 2D band. This reveals the unique underlying electronic band structure of twisted bilayer graphene as well as the unique condition for quantum interference. This finding will help to distinguish among different types of bilayer graphene, and accelerate the exploration of new quantum phenomena in two-dimensional nanomaterials.
More information can be found in the journal Nanotechnology (in press).
About the author
Yanan Wang is a PhD candidate at the University of Houston in the department of Electrical and Computer Engineering, supervised by Jiming Bao. Her research focuses on biophotonic sensing and Raman scatterings of two-dimensional nanomaterials.