Magneto intersubband oscillations in twisted double bilayer graphene

Here we investigate interlayer scattering in twisted double bilayer graphene with an intermediate twist (1.94°) angle. We focus on the decoupled regime where the wavefunctions are bilayer polarized and the device behaves as a weakly coupled double quantum well [1]. Two regimes show enhanced interlayer scattering that we observe through magneto interlayer (intersubband) oscillations [2]. In the regime around the Lifshitz transition, density and temperature dependent resistivity measurements qualitatively indicate increasing trend of interlayer electron-phonon scattering towards the Lifshitz transition that is in accordance with a simple el-ph model. Additionally, interlayer scattering is observed at the onset of the second subband. Observed negative compressibility and the flatness of the bands suggest electron-electron or impurity scattering as the dominant scattering mechanism. Since the nature of the superconducting state in twisted graphene heterostructures remains unknown, our observations can potentially improve the understanding of the coupling mechanism of electrons in twisted graphene.

[1] F. K. de Vries el al., arXiv:2002.05267 1 (2020)
[2] I. A. Dmitriev el al., Rev. Mod. Phys., 84(4):1709, 2012