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Updated: May 15, 2026

Fabricating van der Waals Heterostructures with Precise Rotational Alignment
Published on: July 5, 2019
Unraveling the interlayer-related phonon self-energy renormalization in bilayer graphene
Paulo T Araujo1, Daniela L Mafra, Kentaro Sato
1Department of Electrical Engineering and Computer Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA. ptaraujo@mit.edu
Abstract:
In this letter, we present a step towards understanding the bilayer graphene (2LG) interlayer (IL)-related phonon combination modes and overtones as well as their phonon self-energy renormalizations by using both gate-modulated and laser-energy dependent inelastic scattering spectroscopy. We show that although the IL interactions are weak, their respective phonon renormalization response is significant. Particularly special, the IL interactions are mediated by Van der Waals forces and are fundamental for understanding low-energy phenomena such as transport and infrared optics. Our approach opens up a new route to understanding fundamental properties of IL interactions which can be extended to any graphene-like material, such as MoS₂, WSe₂, oxides and hydroxides. Furthermore, we report a previously elusive crossing between IL-related phonon combination modes in 2LG, which might have important technological applications.
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