Tunable excitons in bilayer graphene

Long Ju^{1

2}, Lei Wang^{1

2}, Ting Cao³, Takashi Taniguchi⁴, Kenji Watanabe⁴, Steven G Louie^{3

5}, Farhan Rana⁶, Jiwoong Park^{1

7}, James Hone⁸, Feng Wang^{9

5

10}, Paul L McEuen^{11

2}

Affiliations

¹ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA.
² Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA.
³ Department of Physics, University of California, Berkeley, CA 94720, USA.
⁴ National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
⁵ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁶ School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA.
⁷ Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
⁸ Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA. plm23@cornell.edu fengwang76@berkeley.edu jh2228@columbia.edu.
⁹ Department of Physics, University of California, Berkeley, CA 94720, USA. plm23@cornell.edu fengwang76@berkeley.edu jh2228@columbia.edu.
¹⁰ Kavli Energy NanoSciences Institute at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
¹¹ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA. plm23@cornell.edu fengwang76@berkeley.edu jh2228@columbia.edu.

PMID: 29146807
DOI: 10.1126/science.aam9175

Tunable excitons in bilayer graphene

Long Ju et al. Science. 2017.

. 2017 Nov 17;358(6365):907-910.

doi: 10.1126/science.aam9175.

Authors

Affiliations

¹ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA.
² Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA.
³ Department of Physics, University of California, Berkeley, CA 94720, USA.
⁴ National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
⁵ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
⁶ School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA.
⁷ Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
⁸ Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA. plm23@cornell.edu fengwang76@berkeley.edu jh2228@columbia.edu.
⁹ Department of Physics, University of California, Berkeley, CA 94720, USA. plm23@cornell.edu fengwang76@berkeley.edu jh2228@columbia.edu.
¹⁰ Kavli Energy NanoSciences Institute at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
¹¹ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY 14853, USA. plm23@cornell.edu fengwang76@berkeley.edu jh2228@columbia.edu.

PMID: 29146807
DOI: 10.1126/science.aam9175

Abstract

Excitons, the bound states of an electron and a hole in a solid material, play a key role in the optical properties of insulators and semiconductors. Here, we report the observation of excitons in bilayer graphene (BLG) using photocurrent spectroscopy of high-quality BLG encapsulated in hexagonal boron nitride. We observed two prominent excitonic resonances with narrow line widths that are tunable from the mid-infrared to the terahertz range. These excitons obey optical selection rules distinct from those in conventional semiconductors and feature an electron pseudospin winding number of 2. An external magnetic field induces a large splitting of the valley excitons, corresponding to a g-factor of about 20. These findings open up opportunities to explore exciton physics with pseudospin texture in electrically tunable graphene systems.

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Tunable excitons in bilayer graphene

Affiliations

Tunable excitons in bilayer graphene

Authors

Affiliations

Abstract

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LinkOut - more resources

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