Title: Evidence of a gate-tunable Mott insulator in a trilayer graphene moiré superlattice

Abstract

The Mott insulator is a central concept in strongly correlated physics and manifests when the repulsive Coulomb interaction between electrons dominates over their kinetic energy. Doping additional carriers into a Mott insulator can give rise to other correlated phenomena such as unusual magnetism and even high-temperature superconductivity. A tunable Mott insulator, where the competition between the Coulomb interaction and the kinetic energy can be varied in situ, can provide an invaluable model system for the study of Mott physics. Here we report the possible realization of such a tunable Mott insulator in a trilayer graphene heterostructure with a moiré superlattice. The combination of the cubic energy dispersion in ABC-stacked trilayer graphene and the narrow electronic minibands induced by the moiré potential leads to the observation of insulating states at the predicted band fillings for the Mott insulator. Moreover, the insulating states in the heterostructure can be tuned: the bandgap can be modulated by a vertical electrical field, and at the same time the electron doping can be modified by a gate to fill the band from one insulating state to another. Here, this opens up exciting opportunities to explore strongly correlated phenomena in two-dimensional moiré superlattice heterostructures.

Authors:

Chen, Guorui  ^[1];

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Jiang, Lili ^[2]; Wu, Shuang ^[2]; Lyu, Bosai ^[3]; Li, Hongyuan ^[3]; Chittari, Bheema Lingam ^[4]; Watanabe, Kenji  ^[5];

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Taniguchi, Takashi ^[5]; Shi, Zhiwen  ^[3];

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Jung, Jeil  ^[4];

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Zhang, Yuanbo ^[6]; Wang, Feng  ^[7]

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+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States); Fudan Univ., Shanghai (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China)
2. Univ. of California, Berkeley, CA (United States)
3. Collaborative Innovation Center of Advanced Microstructures, Nanjing (China); Shanghai Jiao Tong Univ., Shanghai (China)
4. Univ. of Seoul, Seoul (Korea)
5. National Inst. for Materials Science, Tsukuba (Japan)
6. Fudan Univ., Shanghai (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China)
7. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Publication Date:

2019-01-21

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1564017

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Journal Article: Accepted Manuscript

Journal Name:

Nature Physics

Additional Journal Information:

Journal Volume: 15; Journal Issue: 3; Journal ID: ISSN 1745-2473

Publisher:

Nature Publishing Group (NPG)

Country of Publication:

United States

Language:

English

Subject:

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS