Emergence of interfacial polarons from electron-phonon coupling in graphene/h-BN van der Waals heterostructures

Chaoyu Chen, José Avila, Shuopei Wang, Yao Wang, Marcin Mucha-kruczynski, Cheng Shen, Rong Yang, Benjamin Nosarzewski, Thomas P. Devereaux, Guangyu Zhang, Maria-Carmen Asensio

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Abstract

van der Waals heterostructures, vertical stacks of layered materials, offer new opportunities for novel quantum phenomena which are absent in their constituent components. Here we report the emergence of polaron quasiparticles at the interface of graphene/hexagonal boron nitride (h-BN) heterostructures. Using nanospot angle-resolved photoemission spectroscopy, we observe zone-corner replicas of h-BN valence band maxima, with energy spacing coincident with the highest phonon energy of the heterostructure, an indication of Fröhlich polaron formation due to forward-scattering electron–phonon coupling. Parabolic fitting of the h-BN bands yields an effective mass enhancement of ∼2.3, suggesting an intermediate coupling strength. Our theoretical simulations based on Migdal–Eliashberg theory corroborate the experimental results, allowing the extraction of microscopic physical parameters. Moreover, renormalization of graphene π-band is observed due to the hybridization with the h-BN band. Our work generalizes the polaron study from transition metal oxides to van der Waals heterostructures with higher material flexibility, highlighting interlayer coupling as an extra degree of freedom to explore emergent phenomena
Original languageEnglish
Pages (from-to)1082-1087
Number of pages6
JournalNano Letters
Volume18
Issue number2
Early online date5 Jan 2018
DOIs
Publication statusPublished - 14 Feb 2018

Keywords

  • Migdal-Eliashberg theory
  • NanoARPES
  • electron-phonon coupling
  • electronic structure
  • polaron
  • van der Waals heterostructure

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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    Chen, C., Avila, J., Wang, S., Wang, Y., Mucha-kruczynski, M., Shen, C., Yang, R., Nosarzewski, B., Devereaux, T. P., Zhang, G., & Asensio, M-C. (2018). Emergence of interfacial polarons from electron-phonon coupling in graphene/h-BN van der Waals heterostructures. Nano Letters, 18(2), 1082-1087. https://doi.org/10.1021/acs.nanolett.7b04604