Kavli Affiliate: Jie Shan
| First 5 Authors: Liguo Ma, Raghav Chaturvedi, Phuong X. Nguyen, Kenji Watanabe, Takashi Taniguchi
| Summary:
The realization of graphene has provided a bench-top laboratory for quantum
electrodynamics. The low-energy excitations of graphene are two-dimensional
massless Dirac fermions with opposite chiralities at the $pm$K valleys of the
graphene Brillouin zone. It has been speculated that the electron-electron
interactions in graphene could spontaneously break the chiral symmetry to
induce a finite mass for Dirac fermions, in analogue to dynamical mass
generation in elementary particles. The phenomenon is also known as the
relativistic Mott transition and has not been observed in pristine graphene
because the interaction strength is insufficient. Here, we report the
realization of strongly correlated artificial graphene and the observation of
the relativistic Mott transition in twisted WSe2 tetralayers. Using magneto
transport, we show that the first $Gamma$-valley moir’e valence band mimics
the low-energy graphene band structure. At half-band filling, the system
exhibits hallmarks of massless Dirac fermions, including an anomalous Landau
fan originated from a $pi$-Berry phase and a square-root density dependence of
the cyclotron mass. We tune the interaction across the semimetal-insulator
transition by reducing the twist angle below about 2.7 degrees. The emergent
insulator is compatible with an antiferromagnetic Mott insulator. Our results
open the possibility of studying strongly correlated Dirac fermions in a
condensed matter system.
| Search Query: ArXiv Query: search_query=au:”Jie Shan”&id_list=&start=0&max_results=3