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Fabry-Pérot resonances and a crossover to the quantum Hall regime in ballistic graphene quantum point contacts

Ahmad NF 1 , Komatsu K 1 , Iwasaki T 2 , Watanabe K 3 , Taniguchi T 3 , Mizuta H 4 Show all authors , Wakayama Y 1 , Hashim AM 5 , Morita Y 6 , Moriyama S 1 , Nakaharai S 7

Affiliations 

  • 1 International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, 305-0044, Japan
  • 2 International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, 305-0044, Japan
  • 3 Research Center for Functional Materials, NIMS, Tsukuba, Ibaraki, 305-0044, Japan
  • 4 School of Material Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa, 923-1211, Japan
  • 5 Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia
  • 6 Faculty of Engineering, Gunma University, Kiryu, Gunma, 376-8515, Japan
  • 7 International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki, 305-0044, Japan. NAKAHARAI.Shu@nims.go.jp
Sci Rep, 2019 Feb 28;9(1):3031.
PMID: 30816251 DOI: 10.1038/s41598-019-39909-5

Abstract

We report on the observation of quantum transport and interference in a graphene device that is attached with a pair of split gates to form an electrostatically-defined quantum point contact (QPC). In the low magnetic field regime, the resistance exhibited Fabry-Pérot (FP) resonances due to np'n(pn'p) cavities formed by the top gate. In the quantum Hall (QH) regime with a high magnetic field, the edge states governed the phenomena, presenting a unique condition where the edge channels of electrons and holes along a p-n junction acted as a solid-state analogue of a monochromatic light beam. We observed a crossover from the FP to QH regimes in ballistic graphene QPC under a magnetic field with varying temperatures. In particular, the collapse of the QH effect was elucidated as the magnetic field was decreased. Our high-mobility graphene device enabled observation of such quantum coherence effects up to several tens of kelvins. The presented device could serve as one of the key elements in future electronic quantum optic devices.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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