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  1. Article ; Online: Substrate-Dependent Band Structures in Trilayer Graphene/h-BN Heterostructures.

    Che, Shi / Stepanov, Petr / Ge, Supeng / Zhu, Menglin / Wang, Dongying / Lee, Yongjin / Myhro, Kevin / Shi, Yanmeng / Chen, Ruoyu / Pi, Ziqi / Pan, Cheng / Cheng, Bin / Taniguchi, Takashi / Watanabe, Kenji / Barlas, Yafis / Lake, Roger K / Bockrath, Marc / Hwang, Jinwoo / Lau, Chun Ning

    Physical review letters

    2021  Volume 125, Issue 24, Page(s) 246401

    Abstract: The tight-binding model has been spectacularly successful in elucidating the electronic and optical properties of a vast number of materials. Within the tight-binding model, the hopping parameters that determine much of the band structure are often taken ...

    Abstract The tight-binding model has been spectacularly successful in elucidating the electronic and optical properties of a vast number of materials. Within the tight-binding model, the hopping parameters that determine much of the band structure are often taken as constants. Here, using ABA-stacked trilayer graphene as the model system, we show that, contrary to conventional wisdom, the hopping parameters and therefore band structures are not constants, but are systematically variable depending on their relative alignment angle between h-BN. Moreover, the addition or removal of the h-BN substrate results in an inversion of the K and K^{'} valley in trilayer graphene's lowest Landau level. Our work illustrates the oft-ignored and rather surprising impact of the substrates on band structures of 2D materials.
    Language English
    Publishing date 2021-01-07
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.125.246401
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

    Z 4' 58/153: Show issues

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  2. Article ; Online: Quantum parity Hall effect in Bernal-stacked trilayer graphene.

    Stepanov, Petr / Barlas, Yafis / Che, Shi / Myhro, Kevin / Voigt, Greyson / Pi, Ziqi / Watanabe, Kenji / Taniguchi, Takashi / Smirnov, Dmitry / Zhang, Fan / Lake, Roger K / MacDonald, Allan H / Lau, Chun Ning

    Proceedings of the National Academy of Sciences of the United States of America

    2019  Volume 116, Issue 21, Page(s) 10286–10290

    Abstract: The quantum Hall effect has recently been generalized from transport of conserved charges to include transport of other approximately conserved-state variables, including spin and valley, via spin- or valley-polarized boundary states with different ... ...

    Abstract The quantum Hall effect has recently been generalized from transport of conserved charges to include transport of other approximately conserved-state variables, including spin and valley, via spin- or valley-polarized boundary states with different chiralities. Here, we report a class of quantum Hall effect in Bernal- or ABA-stacked trilayer graphene (TLG), the quantum parity Hall (QPH) effect, in which boundary channels are distinguished by even or odd parity under the system's mirror reflection symmetry. At the charge neutrality point, the longitudinal conductance [Formula: see text] is first quantized to [Formula: see text] at a small perpendicular magnetic field [Formula: see text], establishing the presence of four edge channels. As [Formula: see text] increases, [Formula: see text] first decreases to [Formula: see text], indicating spin-polarized counterpropagating edge states, and then, to approximately zero. These behaviors arise from level crossings between even- and odd-parity bulk Landau levels driven by exchange interactions with the underlying Fermi sea, which favor an ordinary insulator ground state in the strong [Formula: see text] limit and a spin-polarized state at intermediate fields. The transitions between spin-polarized and -unpolarized states can be tuned by varying Zeeman energy. Our findings demonstrate a topological phase that is protected by a gate-controllable symmetry and sensitive to Coulomb interactions.
    Language English
    Publishing date 2019-05-03
    Publishing country United States
    Document type Journal Article
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.1820835116
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

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  3. Article ; Online: Broken symmetry quantum Hall states in dual-gated ABA trilayer graphene.

    Lee, Yongjin / Velasco, Jairo / Tran, David / Zhang, Fan / Bao, W / Jing, Lei / Myhro, Kevin / Smirnov, Dmitry / Lau, Chun Ning

    Nano letters

    2013  Volume 13, Issue 4, Page(s) 1627–1631

    Abstract: ABA-stacked trilayer graphene is a unique 2D electron system with mirror reflection symmetry and unconventional quantum Hall effect. We present low-temperature transport measurements on dual-gated suspended trilayer graphene in the quantum Hall (QH) ... ...

    Abstract ABA-stacked trilayer graphene is a unique 2D electron system with mirror reflection symmetry and unconventional quantum Hall effect. We present low-temperature transport measurements on dual-gated suspended trilayer graphene in the quantum Hall (QH) regime. We observe QH plateaus at filling factors ν = -8, -2, 2, 6, and 10, which is in agreement with the full-parameter tight binding calculations. In high magnetic fields, odd-integer plateaus are also resolved, indicating almost complete lifting of the 12-fold degeneracy of the lowest Landau level (LL). Under an out-of-plane electric field E(perpendicular), we observe degeneracy breaking and transitions between QH plateaus. Interestingly, depending on its direction, E(perpendicular) selectively breaks the LL degeneracies in the electron-doped or hole-doped regimes. Our results underscore the rich interaction-induced phenomena in trilayer graphene.
    MeSH term(s) Electrons ; Graphite/chemistry ; Magnetic Fields ; Quantum Theory
    Chemical Substances Graphite (7782-42-5)
    Language English
    Publishing date 2013-03-27
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1530-6992
    ISSN (online) 1530-6992
    DOI 10.1021/nl4000757
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Evidence of Topological Nodal-Line Fermions in ZrSiSe and ZrSiTe.

    Hu, Jin / Tang, Zhijie / Liu, Jinyu / Liu, Xue / Zhu, Yanglin / Graf, David / Myhro, Kevin / Tran, Son / Lau, Chun Ning / Wei, Jiang / Mao, Zhiqiang

    Physical review letters

    2016  Volume 117, Issue 1, Page(s) 16602

    Abstract: A Dirac nodal-line semimetal phase, which represents a new quantum state of topological materials, has been experimentally realized only in a few systems, including PbTaSe_{2}, PtSn_{4}, and ZrSiS. In this Letter, we report evidence of nodal-line ... ...

    Abstract A Dirac nodal-line semimetal phase, which represents a new quantum state of topological materials, has been experimentally realized only in a few systems, including PbTaSe_{2}, PtSn_{4}, and ZrSiS. In this Letter, we report evidence of nodal-line fermions in ZrSiSe and ZrSiTe probed in de Haas-van Alphen quantum oscillations. Although ZrSiSe and ZrSiTe share a similar layered structure with ZrSiS, our studies show the Fermi surface (FS) enclosing a Dirac nodal line has a 2D character in ZrSiTe, in contrast with 3D-like FS in ZrSiSe and ZrSiS. Another important property revealed in our experiment is that the nodal-line fermion density in this family of materials (∼10^{20}  cm^{-3}) is much higher than the Dirac fermion density of other topological materials with discrete nodes. In addition, we have demonstrated ZrSiSe and ZrSiTe single crystals can be thinned down to 2D atomic thin layers through microexfoliation, which offers the first platform to explore exotic properties of topological nodal-line fermions in low dimensions.
    Language English
    Publishing date 2016-07-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.117.016602
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

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  5. Article ; Online: In situ observation of electrostatic and thermal manipulation of suspended graphene membranes.

    Bao, Wenzhong / Myhro, Kevin / Zhao, Zeng / Chen, Zhen / Jang, Wanyoung / Jing, Lei / Miao, Feng / Zhang, Hang / Dames, Chris / Lau, Chun Ning

    Nano letters

    2012  Volume 12, Issue 11, Page(s) 5470–5474

    Abstract: Graphene is nature's thinnest elastic membrane, and its morphology has important impacts on its electrical, mechanical, and electromechanical properties. Here we report manipulation of the morphology of suspended graphene via electrostatic and thermal ... ...

    Abstract Graphene is nature's thinnest elastic membrane, and its morphology has important impacts on its electrical, mechanical, and electromechanical properties. Here we report manipulation of the morphology of suspended graphene via electrostatic and thermal control. By measuring the out-of-plane deflection as a function of applied gate voltage and number of layers, we show that graphene adopts a parabolic profile at large gate voltages with inhomogeneous distribution of charge density and strain. Unclamped graphene sheets slide into the trench under tension; for doubly clamped devices, the results are well-accounted for by membrane deflection with effective Young's modulus E = 1.1 TPa. Upon cooling to 100 K, we observe buckling-induced ripples in the central portion and large upward buckling of the free edges, which arises from graphene's large negative thermal expansion coefficient.
    Language English
    Publishing date 2012-10-15
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1530-6992
    ISSN (online) 1530-6992
    DOI 10.1021/nl301836q
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Book ; Online: Generation of photovoltage in graphene on a femtosecond time scale through efficient carrier heating

    Tielrooij, Klaas-Jan / Piatkowski, Lukasz / Massicotte, Mathieu / Woessner, Achim / Ma, Qiong / Lee, Yongjin / Myhro, Kevin Scott / Lau, Chun Ning / Jarillo-Herrero, Pablo / van Hulst, Niek F. / Koppens, Frank H. L.

    2015  

    Abstract: Graphene is a promising material for ultrafast and broadband photodetection. Earlier studies addressed the general operation of graphene-based photo-thermoelectric devices, and the switching speed, which is limited by the charge carrier cooling time, on ... ...

    Abstract Graphene is a promising material for ultrafast and broadband photodetection. Earlier studies addressed the general operation of graphene-based photo-thermoelectric devices, and the switching speed, which is limited by the charge carrier cooling time, on the order of picoseconds. However, the generation of the photovoltage could occur at a much faster time scale, as it is associated with the carrier heating time. Here, we measure the photovoltage generation time and find it to be faster than 50 femtoseconds. As a proof-of-principle application of this ultrafast photodetector, we use graphene to directly measure, electrically, the pulse duration of a sub-50 femtosecond laser pulse. The observation that carrier heating is ultrafast suggests that energy from absorbed photons can be efficiently transferred to carrier heat. To study this, we examine the spectral response and find a constant spectral responsivity between 500 and 1500 nm. This is consistent with efficient electron heating. These results are promising for ultrafast femtosecond and broadband photodetector applications.

    Comment: 6 pages, 4 figures
    Keywords Condensed Matter - Mesoscale and Nanoscale Physics
    Subject code 621
    Publishing date 2015-04-24
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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