We report planar tunneling spectroscopy measurements on metal-WSe2-twisted bilayer graphene heterostructures across a broad range of gate and bias voltages. The observed experimental features are attributed to phonon-assisted tunneling and the significantly high density of states within the moir\'e bands. A notable finding is the enhanced phonon-assisted tunneling in twisted bilayer graphene compared to Bernal bilayer graphene, which arises from a more relaxed in-plane momentum matching criterion. Theoretical calculations of phonon dispersions enable us to identify low-energy phonon modes in both Bernal and twisted bilayers of graphene, thereby elucidating the underlying mechanism of tunneling. Our results establish planar tunneling as a versatile tool to further understand electron-phonon coupling in twisted van der Waals materials.
@article{arxiv.2507.12991,
title = {Enhanced Phonon-Assisted Tunneling in Metal -- Twisted Bilayer Graphene Junctions},
author = {Radhika Soni and Suvronil Datta and Robin Bajaj and Saisab Bhowmik and Shinjan Mandal and Baladitya Suri and Kenji Watanabe and Takashi Taniguchi and Manish Jain and U. Chandni},
journal= {arXiv preprint arXiv:2507.12991},
year = {2025}
}