DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Signatures of tunable superconductivity in a trilayer graphene moiré superlattice

Journal Article · · Nature (London)
 [1];  [2];  [3];  [2];  [4];  [5];  [6];  [6];  [7];  [7];  [8];  [6];  [4];  [9];  [3]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); SIMES
  2. Stanford Univ., CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
  4. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., CA (United States)
  5. Univ. of California, Berkeley, CA (United States)
  6. Shanghai Jiao Tong Univ. (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China)
  7. National Inst. for Materials Science (NIMS), Tsukuba (Japan)
  8. Univ. of Seoul, Seoul (Korea, Republic of)
  9. Collaborative Innovation Center of Advanced Microstructures, Nanjing (China); Fudan Univ., Shanghai (China)

Understanding the mechanism of high-transition-temperature (high-Tc) superconductivity is a central problem in condensed matter physics. It is often speculated that high-Tc superconductivity arises in a doped Mott insulator1 as described by the Hubbard model2,3,4. An exact solution of the Hubbard model, however, is extremely challenging owing to the strong electron–electron correlation in Mott insulators. Therefore, it is highly desirable to study a tunable Hubbard system, in which systematic investigations of the unconventional superconductivity and its evolution with the Hubbard parameters can deepen our understanding of the Hubbard model. Here we report signatures of tunable superconductivity in an ABC-trilayer graphene (TLG) and hexagonal boron nitride (hBN) moiré superlattice. Unlike in ‘magic angle’ twisted bilayer graphene, theoretical calculations show that under a vertical displacement field, the ABC-TLG/hBN heterostructure features an isolated flat valence miniband associated with a Hubbard model on a triangular superlattice5,6 where the bandwidth can be tuned continuously with the vertical displacement field. Upon applying such a displacement field we find experimentally that the ABC-TLG/hBN superlattice displays Mott insulating states below 20 kelvin at one-quarter and one-half fillings of the states, corresponding to one and two holes per unit cell, respectively. Upon further cooling, signatures of superconductivity (‘domes’) emerge below 1 kelvin for the electron- and hole-doped sides of the one-quarter-filling Mott state. The electronic behaviour in the ABC-TLG/hBN superlattice is expected to depend sensitively on the interplay between the electron–electron interaction and the miniband bandwidth. By varying the vertical displacement field, we demonstrate transitions from the candidate superconductor to Mott insulator and metallic phases. Our study shows that ABC-TLG/hBN heterostructures offer attractive model systems in which to explore rich correlated behaviour emerging in the tunable triangular Hubbard model.

Research Organization:
Energy Frontier Research Centers (EFRC) (United States). Center for Novel Pathways to Quantum Coherence in Materials (NPQC); Stanford Univ., Redwood City, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
Grant/Contract Number:
AC02-76SF00515; AC02-05CH11231
OSTI ID:
1545526
Alternate ID(s):
OSTI ID: 1619126
Journal Information:
Nature (London), Journal Name: Nature (London) Journal Issue: 7768 Vol. 572; ISSN 0028-0836
Publisher:
Nature Publishing GroupCopyright Statement
Country of Publication:
United States
Language:
English

References (45)

Bridging Hubbard model physics and quantum Hall physics in trilayer graphene / h − BN moiré superlattice journal May 2019
Electron correlations in narrow energy bands. II. The degenerate band case journal January 1964
Emergence of superlattice Dirac points in graphene on hexagonal boron nitride journal March 2012
Trigonal warping and Berry's phase N pi in ABC-stacked multilayer graphene text January 2009
Metal-insulator transitions journal June 1991
Topological Superconductivity in Twisted Multilayer Graphene text January 2018
Competition between spontaneous symmetry breaking and single-particle gaps in trilayer graphene journal December 2014
Tuning superconductivity in twisted bilayer graphene journal January 2019
Topological valley transport at bilayer graphene domain walls journal April 2015
Hofstadter’s butterfly and the fractal quantum Hall effect in moiré superlattices journal May 2013
Nearly flat Chern bands in moiré superlattices journal February 2019
The Basis of the Electron Theory of Metals, with Special Reference to the Transition Metals journal July 1949
Stacking-Dependent Band Gap and Quantum Transport in Trilayer Graphene text January 2011
Isospin Pomeranchuk effect in twisted bilayer graphene journal April 2021
Atomic and electronic reconstruction at the van der Waals interface in twisted bilayer graphene journal April 2019
Unconventional superconductivity in magic-angle graphene superlattices journal March 2018
Cloning of Dirac fermions in graphene superlattices journal May 2013
Correlated insulator behaviour at half-filling in magic-angle graphene superlattices journal March 2018
Composite fermions and broken symmetries in graphene journal January 2015
Emergence of Tertiary Dirac Points in Graphene Moiré Superlattices journal May 2017
Evidence of a gate-tunable Mott insulator in a trilayer graphene moiré superlattice journal January 2019
Atomic and electronic reconstruction at van der Waals interface in twisted bilayer graphene text January 2018
Topological Superconductivity in Twisted Multilayer Graphene journal August 2018
Trigonal warping and Berry’s phase N π in ABC-stacked multilayer graphene journal October 2009
Charge imbalance observed in voltage-biased superconductor–normal tunnel junctions journal April 2006
Transport studies of dual-gated ABC and ABA trilayer graphene: band gap opening and band structure tuning in very large perpendicular electric field text January 2013
Gate-Tunable Topological Flat Bands in Trilayer Graphene Boron-Nitride Moiré Superlattices journal January 2019
Epitaxial growth of single-domain graphene on hexagonal boron nitride journal July 2013
Strongly correlated Chern insulators in magic-angle twisted bilayer graphene journal December 2020
One-Dimensional Electrical Contact to a Two-Dimensional Material journal October 2013
Electrically tunable low-density superconductivity in a monolayer topological insulator journal October 2018
Massive Dirac Fermions and Hofstadter Butterfly in a van der Waals Heterostructure journal May 2013
Band structure of A B C -stacked graphene trilayers journal July 2010
The influence of fluctuation pairing of electrons on the conductivity of normal metal journal February 1968
Doping a Mott insulator: Physics of high-temperature superconductivity journal January 2006
Cloning of Dirac fermions in graphene superlattices text January 2012
Tunable interacting composite fermion phases in a half-filled bilayer-graphene Landau level journal September 2017
The experimental observation of quantum Hall effect of l=3 chiral quasiparticles in trilayer graphene journal September 2011
Observation of an electrically tunable band gap in trilayer graphene journal September 2011
Stacking-dependent band gap and quantum transport in trilayer graphene journal September 2011
Band Structure of ABC-Stacked Graphene Trilayers text January 2010
Transport Studies of Dual-Gated ABC and ABA Trilayer Graphene: Band Gap Opening and Band Structure Tuning in Very Large Perpendicular Electric Fields journal January 2013
Tuning superconductivity in twisted bilayer graphene text January 2018
Ising pairing in superconducting NbSe2 atomic layers journal November 2015
Metal-insulator transitions journal October 1998

Cited By (26)

Topological sliding moiré heterostructure journal January 2020
Strong correlations and orbital texture in single-layer 1T-TaSe2 journal January 2020
Superfluid weight and Berezinskii-Kosterlitz-Thouless transition temperature of twisted bilayer graphene journal February 2020
Tunable crystal symmetry in graphene–boron nitride heterostructures with coexisting moiré superlattices journal September 2019
Topological charge pumping in twisted bilayer graphene text January 2019
Spin liquids and pseudogap metals in the SU(4) Hubbard model in a moiré superlattice journal January 2020
Topological charge pumping in twisted bilayer graphene journal January 2020
Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice journal March 2020
Classification of Critical Points in Energy Bands Based on Topology, Scaling and Symmetry text January 2019
Graphene-based spinmechatronic valve journal October 2019
Correlated states in twisted double bilayer graphene journal March 2020
Landau level degeneracy in twisted bilayer graphene: Role of symmetry breaking journal September 2019
Interacting valley Chern insulator and its topological imprint on moiré superconductors journal October 2019
Superconductors, orbital magnets and correlated states in magic-angle bilayer graphene journal October 2019
Classification of critical points in energy bands based on topology, scaling, and symmetry journal March 2020
Geometric and Conventional Contribution to the Superfluid Weight in Twisted Bilayer Graphene journal December 2019
Reconstruction of the Bi 2 Sr 2 CaCu 2 O 8 + δ Fermi surface journal December 2019
2D Materials for Large‐Area Flexible Thermoelectric Devices journal November 2019
Geometric and conventional contribution to superfluid weight in twisted bilayer graphene text January 2019
Correlated states in twisted double bilayer graphene text January 2019
Multifunctional inorganic nanomaterials for energy applications journal January 2020
Classifying superconductivity in Moiré graphene superlattices journal January 2020
Large-area epitaxial growth of curvature-stabilized ABC trilayer graphene journal January 2020
p-wave superconductivity in iron-based superconductors journal October 2019
Cleaning interfaces in layered materials heterostructures journal December 2018
Pairing and non-Fermi liquid behavior in partially flat-band systems: Beyond nesting physics journal January 2020