Bilayer Wigner crystals in a transition metal dichalcogenide heterostructure

You Zhou; Jiho Sung; Elise Brutschea; Ilya Esterlis; Yao Wang; Giovanni Scuri; Ryan J Gelly; Hoseok Heo; Takashi Taniguchi; Kenji Watanabe; Gergely Zaránd; Mikhail D Lukin; Philip Kim; Eugene Demler; Hongkun Park

doi:10.1038/s41586-021-03560-w

Bilayer Wigner crystals in a transition metal dichalcogenide heterostructure

Nature. 2021 Jul;595(7865):48-52. doi: 10.1038/s41586-021-03560-w. Epub 2021 Jun 30.

Authors

You Zhou^{1

2

3}, Jiho Sung^{1

2}, Elise Brutschea¹, Ilya Esterlis², Yao Wang^{2

4}, Giovanni Scuri², Ryan J Gelly², Hoseok Heo^{1

2}, Takashi Taniguchi⁵, Kenji Watanabe⁶, Gergely Zaránd⁷, Mikhail D Lukin², Philip Kim^{2

8}, Eugene Demler^{9

10}, Hongkun Park^{11

12}

Affiliations

¹ Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
² Department of Physics, Harvard University, Cambridge, MA, USA.
³ Department of Materials Science and Engineering, University of Maryland, College Park, MD, USA.
⁴ Department of Physics and Astronomy, Clemson University, Clemson, SC, USA.
⁵ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan.
⁶ Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan.
⁷ MTA-BME Quantum Dynamics and Correlations Research Group, Institute of Physics, Budapest University of Technology and Economics, Budapest, Hungary.
⁸ John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
⁹ Department of Physics, Harvard University, Cambridge, MA, USA. demler@physics.harvard.edu.
¹⁰ Institute for Theoretical Physics, ETH Zürich, Zürich, Switzerland. demler@physics.harvard.edu.
¹¹ Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA. Hongkun_Park@harvard.edu.
¹² Department of Physics, Harvard University, Cambridge, MA, USA. Hongkun_Park@harvard.edu.

PMID: 34194017
DOI: 10.1038/s41586-021-03560-w

Abstract

One of the first theoretically predicted manifestations of strong interactions in many-electron systems was the Wigner crystal^1-3, in which electrons crystallize into a regular lattice. The crystal can melt via either thermal or quantum fluctuations⁴. Quantum melting of the Wigner crystal is predicted to produce exotic intermediate phases^5,6 and quantum magnetism^7,8 because of the intricate interplay of Coulomb interactions and kinetic energy. However, studying two-dimensional Wigner crystals in the quantum regime has often required a strong magnetic field^9-11 or a moiré superlattice potential^12-15, thus limiting access to the full phase diagram of the interacting electron liquid. Here we report the observation of bilayer Wigner crystals without magnetic fields or moiré potentials in an atomically thin transition metal dichalcogenide heterostructure, which consists of two MoSe₂ monolayers separated by hexagonal boron nitride. We observe optical signatures of robust correlated insulating states at symmetric (1:1) and asymmetric (3:1, 4:1 and 7:1) electron doping of the two MoSe₂ layers at cryogenic temperatures. We attribute these features to bilayer Wigner crystals composed of two interlocked commensurate triangular electron lattices, stabilized by inter-layer interaction¹⁶. The Wigner crystal phases are remarkably stable, and undergo quantum and thermal melting transitions at electron densities of up to 6 × 10¹² per square centimetre and at temperatures of up to about 40 kelvin. Our results demonstrate that an atomically thin heterostructure is a highly tunable platform for realizing many-body electronic states and probing their liquid-solid and magnetic quantum phase transitions^4-8,17.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.