Mott and generalized Wigner crystal states in WSe2/WS2 moiré superlattices

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

Abstract

Moiré superlattices can be used to engineer strongly correlated electronic states in two-dimensional van der Waals heterostructures, as recently demonstrated in the correlated insulating and superconducting states observed in magic-angle twisted-bilayer graphene and ABC trilayer graphene/boron nitride moiré superlattices1–4. Transition metal dichalcogenide moiré heterostructures provide another model system for the study of correlated quantum phenomena5 because of their strong light–matter interactions and large spin–orbit coupling. However, experimental observation of correlated insulating states in this system is challenging with traditional transport techniques. Here we report the optical detection of strongly correlated phases in semiconducting WSe2/WS2 moiré superlattices. We use a sensitive optical detection technique and reveal a Mott insulator state at one hole per superlattice site and surprising insulating phases at 1/3 and 2/3 filling of the superlattice, which we assign to generalized Wigner crystallization on the underlying lattice6–11. Furthermore, the spin–valley optical selection rules12–14 of transition metal dichalcogenide heterostructures allow us to optically create and investigate low-energy excited spin states in the Mott insulator. We measure a very long spin relaxation lifetime of many microseconds in the Mott insulating state, orders of magnitude longer than that of charge excitations. Our studies highlight the value of using moiré superlattices beyond graphene to explore correlated physics.

Detaljer

Författare
  • Emma C. Regan
  • Danqing Wang
  • Chenhao Jin
  • M. Iqbal Bakti Utama
  • Beini Gao
  • Xin Wei
  • Sihan Zhao
  • Wenyu Zhao
  • Zuocheng Zhang
  • Kentaro Yumigeta
  • Mark Blei
  • Johan D. Carlström
  • Kenji Watanabe
  • Takashi Taniguchi
  • Sefaattin Tongay
  • Michael Crommie
  • Alex Zettl
  • Feng Wang
Externa organisationer
  • University of California, Berkeley
  • Lawrence Berkeley National Laboratory
  • Huazhong University of Science and Technology
  • University of the Chinese Academy of Sciences
  • Arizona State University
  • National Institute for Material Science
  • Lund University
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Fysik
Originalspråkengelska
Sidor (från-till)359-363
Antal sidor5
TidskriftNature
Volym579
Utgåva nummer7799
StatusPublished - 2020
PublikationskategoriForskning
Peer review utfördJa
Externt publiceradJa