Orbitally Controlled Quantum Hall States in Decoupled Two‐Bilayer Graphene Sheets
Abstract The authors report on integer and fractional quantum Hall states in a stack of two twisted Bernal bilayer graphene sheets. By exploiting the momentum mismatch in reciprocal space, the single‐particle tunneling between both bilayers is suppressed. Since the bilayers are spatially separated b...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2023-08-01
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| Series: | Advanced Science |
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| Online Access: | https://doi.org/10.1002/advs.202300574 |
| _version_ | 1797742697333653504 |
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| author | Soyun Kim Dohun Kim Kenji Watanabe Takashi Taniguchi Jurgen H. Smet Youngwook Kim |
| author_facet | Soyun Kim Dohun Kim Kenji Watanabe Takashi Taniguchi Jurgen H. Smet Youngwook Kim |
| author_sort | Soyun Kim |
| collection | DOAJ |
| description | Abstract The authors report on integer and fractional quantum Hall states in a stack of two twisted Bernal bilayer graphene sheets. By exploiting the momentum mismatch in reciprocal space, the single‐particle tunneling between both bilayers is suppressed. Since the bilayers are spatially separated by only 0.34 nm, the stack benefits from strong interlayer Coulombic interactions. These interactions can cause the formation of a Bose–Einstein condensate. Indeed, such a condensate is observed for half‐filling in each bilayer sheet. However, only when the partially filled levels have orbital index 1. It is absent for partially filled levels with orbital index 0. This discrepancy is tentatively attributed to the role of skyrmion/anti‐skyrmion pair excitations and the dependence of the energy of these excitations on the orbital index. The application of asymmetric top and bottom gate voltages enables to influence the orbital nature of the electronic states of the graphene bilayers at the chemical potential and to navigate in orbital mixed space. The latter hosts an even denominator fractional quantum Hall state at total filling of −3/2. These observations suggest a unique edge reconstruction involving both electrons and chiral p‐wave composite fermions. |
| first_indexed | 2024-03-12T14:44:16Z |
| format | Article |
| id | doaj.art-b4f7452eb3714b0d9af248f8106f81f9 |
| institution | Directory Open Access Journal |
| issn | 2198-3844 |
| language | English |
| last_indexed | 2024-03-12T14:44:16Z |
| publishDate | 2023-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Advanced Science |
| spelling | doaj.art-b4f7452eb3714b0d9af248f8106f81f92023-08-16T02:23:01ZengWileyAdvanced Science2198-38442023-08-011023n/an/a10.1002/advs.202300574Orbitally Controlled Quantum Hall States in Decoupled Two‐Bilayer Graphene SheetsSoyun Kim0Dohun Kim1Kenji Watanabe2Takashi Taniguchi3Jurgen H. Smet4Youngwook Kim5Department of Physics and Chemistry Daegu Gyeongbuk Institute of Science and Technology (DGIST) Daegu 42988 Republic of KoreaDepartment of Physics and Chemistry Daegu Gyeongbuk Institute of Science and Technology (DGIST) Daegu 42988 Republic of KoreaResearch Center for Functional Materials National Institute for Materials Science Tsukuba 305‐0044 JapanInternational Center for Materials Nanoarchitectonics National Institute for Materials Science Tsukuba 305‐0044 JapanMax Planck Institute for Solid State Research 70569 Stuttgart GermanyDepartment of Physics and Chemistry Daegu Gyeongbuk Institute of Science and Technology (DGIST) Daegu 42988 Republic of KoreaAbstract The authors report on integer and fractional quantum Hall states in a stack of two twisted Bernal bilayer graphene sheets. By exploiting the momentum mismatch in reciprocal space, the single‐particle tunneling between both bilayers is suppressed. Since the bilayers are spatially separated by only 0.34 nm, the stack benefits from strong interlayer Coulombic interactions. These interactions can cause the formation of a Bose–Einstein condensate. Indeed, such a condensate is observed for half‐filling in each bilayer sheet. However, only when the partially filled levels have orbital index 1. It is absent for partially filled levels with orbital index 0. This discrepancy is tentatively attributed to the role of skyrmion/anti‐skyrmion pair excitations and the dependence of the energy of these excitations on the orbital index. The application of asymmetric top and bottom gate voltages enables to influence the orbital nature of the electronic states of the graphene bilayers at the chemical potential and to navigate in orbital mixed space. The latter hosts an even denominator fractional quantum Hall state at total filling of −3/2. These observations suggest a unique edge reconstruction involving both electrons and chiral p‐wave composite fermions.https://doi.org/10.1002/advs.202300574Bose–Einstein condensationfractional quantum Hall effectquantum Hall effecttwisted double bilayer graphene |
| spellingShingle | Soyun Kim Dohun Kim Kenji Watanabe Takashi Taniguchi Jurgen H. Smet Youngwook Kim Orbitally Controlled Quantum Hall States in Decoupled Two‐Bilayer Graphene Sheets Advanced Science Bose–Einstein condensation fractional quantum Hall effect quantum Hall effect twisted double bilayer graphene |
| title | Orbitally Controlled Quantum Hall States in Decoupled Two‐Bilayer Graphene Sheets |
| title_full | Orbitally Controlled Quantum Hall States in Decoupled Two‐Bilayer Graphene Sheets |
| title_fullStr | Orbitally Controlled Quantum Hall States in Decoupled Two‐Bilayer Graphene Sheets |
| title_full_unstemmed | Orbitally Controlled Quantum Hall States in Decoupled Two‐Bilayer Graphene Sheets |
| title_short | Orbitally Controlled Quantum Hall States in Decoupled Two‐Bilayer Graphene Sheets |
| title_sort | orbitally controlled quantum hall states in decoupled two bilayer graphene sheets |
| topic | Bose–Einstein condensation fractional quantum Hall effect quantum Hall effect twisted double bilayer graphene |
| url | https://doi.org/10.1002/advs.202300574 |
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