Title: Gaps induced by inversion symmetry breaking and second-generation Dirac cones in graphene/hexagonal boron nitride

Abstract

Graphene/hexagonal boron nitride (h-BN) has emerged as a model van der Waals heterostructure as the superlattice potential, which is induced by lattice mismatch and crystal orientation, gives rise to various novel quantum phenomena, such as the self-similar Hofstadter butterfly states. Although the newly generated second-generation Dirac cones (SDCs) are believed to be crucial for understanding such intriguing phenomena, fundamental knowledge of SDCs, such as locations and dispersion, and the effect of inversion symmetry breaking on the gap opening, still remains highly debated due to the lack of direct experimental results. In this work we report direct experimental results on the dispersion of SDCs in 0°-aligned graphene/h-BN heterostructures using angle-resolved photoemission spectroscopy. Our data unambiguously reveal SDCs at the corners of the superlattice Brillouin zone, and at only one of the two superlattice valleys. Moreover, gaps of approximately 100 meV and approximately 160 meV are observed at the SDCs and the original graphene Dirac cone, respectively. Our work highlights the important role of a strong inversion-symmetry-breaking perturbation potential in the physics of graphene/h-BN, and fills critical knowledge gaps in the band structure engineering of Dirac fermions by a superlattice potential.

Authors:

Wang, Eryin ^[1]; Lu, Xiaobo ^[2]; Ding, Shijie ^[1]; Yao, Wei  ^[1];

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• Search OSTI.GOV for ORCID "0000-0003-4518-3632"
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Yan, Mingzhe ^[1]; Wan, Guoliang ^[1]; Deng, Ke ^[1]; Wang, Shuopei ^[2]; Chen, Guorui ^[3]; Ma, Liguo ^[3]; Jung, Jeil  ^[4];

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• Search OSTI.GOV for ORCID "0000-0003-2523-0905"
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Fedorov, Alexei V. ^[5]; Zhang, Yuanbo ^[3]; Zhang, Guangyu ^[6]; Zhou, Shuyun ^[7]

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+ Show Author Affiliations

1. Tsinghua Univ., Beijing (China). State Key Lab. of Low Dimensional Quantum Physics and Dept. of Physics
2. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics. Beijing National Lab. for Condensed Matter Physics (BNLCP-CAS)
3. Fudan Univ., Shanghai (China). State Key Lab. of Surface Physics and Dept. of Physics
4. Univ. of Seoul (Korea, Republic of). Dept. of Physics
5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
6. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics. Beijing National Lab. for Condensed Matter Physics (BNLCP-CAS); Collaborative Innovation Center of Quantum Matter (CICQM), Beijing (China)
7. Tsinghua Univ., Beijing (China). State Key Lab. of Low Dimensional Quantum Physics and Dept. of Physics; Collaborative Innovation Center of Quantum Matter (CICQM), Beijing (China)

Publication Date:

2016-08-22

Research Org.:

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

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Natural Science Foundation of China (NNSFC); Ministry of Science and Technology (MOST); Tsinghua Univ., Beijing (China)

OSTI Identifier:

1436607

Grant/Contract Number:  

AC02-05CH11231; 11274191; 11334006; 11427903; 2015CB921001; 2016YFA0301004; 2012Z02285

Resource Type:

Journal Article: Accepted Manuscript

Journal Name:

Nature Physics

Additional Journal Information:

Journal Volume: 12; Journal Issue: 12; Journal ID: ISSN 1745-2473

Publisher:

Nature Publishing Group (NPG)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 36 MATERIALS SCIENCE; Electronic properties and materials; Surfaces, interfaces and thin films