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SUMMARY:Electron Correlation and Coupling with Phonon in the Rhombohedral 
 Stacked Graphene - Prof. Long Ju\, Department of Physics\, Massachusetts I
 nstitute of Technology\, USA
DTSTART:20230126T110000Z
DTEND:20230126T120000Z
UID:TALK196369@talks.cam.ac.uk
CONTACT:Dr Wladislaw Michailow
DESCRIPTION:ABC-stacked trilayer graphene/hexagonal boron nitride moiré s
 uperlattice (TLG/hBN) has emerged as a playground for correlated electron 
 physics. A spectroscopy study of this system is\, however\, challenging du
 e to the device configuration. In this talk\, I will introduce our recent 
 efforts on FTIR photocurrent spectroscopy measurements of dual-gated TLG/h
 BN. We observed strong gate-tunable optical transitions that originated fr
 om the moiré flat band. At half-filling of the valence flat band\, a broa
 d absorption peak emerges at ~18 meV\, indicating direct optical excitatio
 n across an emerging Mott gap. Furthermore\, I will talk about a unique mo
 iré-enabled interlayer electron-phonon coupling phenomenon in this system
 . The ZO phonon in hBN hybridizes with electron-hole excitations in trilay
 er graphene and appear as an asymmetric peak in the photocurrent spectrum.
  This Fano line-shaped peak evolves continuously as we tune the displaceme
 nt field. If time permits\, I will also talk about our recent work on prob
 ing the electron correlation and topology in rhombohedral stacked graphene
  in the absence of moiré.\n\nReferences:\n1. Ju\, L. et al.\, "Tunable ex
 citons in bilayer graphene." Science 358.6365 (2017): 907-910.\n\n2. Han\,
  T. et al.\, "Accurate Measurement of the Gap of Graphene/h−BN Moiré Su
 perlattice through Photocurrent Spectroscopy." Physical Review Letters 126
 .14 (2021): 146402.\n\n3. Yang\, J. et al.\, "Spectroscopy signatures of e
 lectron correlations in a trilayer graphene/hBN moiré superlattice." Scie
 nce 375.6586 (2022): 1295-1299.
LOCATION:Mott Seminar Room (531)\, Cavendish Laboratory\, Department of Ph
 ysics
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