Broken Symmetry Quantum Hall States in Dual-Gated ABA Trilayer Graphene

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

doi:10.1021/nl4000757

Cited by 46 publications

(61 citation statements)

References 55 publications

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“…The ratio between the resistance of the "on" state at high carrier density and the "off" state at the CNP reaches 10 6 at large |D|, which is the largest ratio reported for trilayer graphene. The observed gate dependence of R 23 unambiguously demonstrates the opening of a band gap in the ABC-TG portion of the device.…”

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confidence: 65%

Transport Studies of Dual-Gated ABC and ABA Trilayer Graphene: Band Gap Opening and Band Structure Tuning in Very Large Perpendicular Electric Fields

et al. 2013

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Transport Studies of Dual-Gated ABC and ABA Trilayer Graphene: Band Gap Opening and Band Structure Tuning in Very Large Perpendicular Electric Fields

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“…This results in a series of QH phase transitions. Note that a similar experiment has been performed by Lee et al [6] but the quantum Hall staircase details were obscured by charge inhomogeneity. This behavior is also observed in device 1-see Fig.…”

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confidence: 75%

“…The electronic properties of ABA-stacked trilayer graphene (TLG) are being intensively investigated [1][2][3][4][5][6] due to its distinct band structure which consists of two overlapping monolayer-graphene-like (MLG-like) and bilayergraphene-like (BLG-like) bands [1,[7][8][9][10][11][12][13][14]. However, in contrast to MLG and BLG, which are gapless, both subbands in ABA-stacked TLG are gapped, with small masses of the order of a few meV.…”

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confidence: 99%

Landau Level Splittings, Phase Transitions, and Nonuniform Charge Distribution in Trilayer Graphene

et al. 2016

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We report on magnetotransport studies of dual-gated, Bernal-stacked trilayer graphene (TLG) encapsulated in boron nitride crystals. We observe a quantum Hall effect staircase which indicates a complete lifting of the 12-fold degeneracy of the zeroth Landau level. As a function of perpendicular electric field, our data exhibit a sequence of phase transitions between all integer quantum Hall states in the filling factor interval −8 < ν < 0. We develop a theoretical model and argue that, in contrast to monolayer and bilayer graphene, the observed Landau level splittings and quantum Hall phase transitions can be understood within a single-particle picture, but imply the presence of a charge density imbalance between the inner and outer layers of TLG, even at charge neutrality and zero transverse electric field. Our results indicate the importance of a previously unaccounted band structure parameter which, together with a more accurate estimate of the other tight-binding parameters, results in a significantly improved determination of the electronic and Landau level structure of TLG. DOI: 10.1103/PhysRevLett.117.066601 The electronic properties of ABA-stacked trilayer graphene (TLG) are being intensively investigated [1-6] due to its distinct band structure which consists of two overlapping monolayer-graphene-like (MLG-like) and bilayergraphene-like (BLG-like) bands [1,[7][8][9][10][11][12][13][14]. However, in contrast to MLG and BLG, which are gapless, both subbands in ABA-stacked TLG are gapped, with small masses of the order of a few meV.One of the most interesting characteristics of ABAstacked TLG compared to other graphene systems is the way in which its band structure is modified by a perpendicular electric field [2,12,[14][15][16][17][18]. Theory predicts that a weak electric field hybridizes the MLG-like and BLG-like bands, rather than inducing a band gap, as in BLG or ABC-stacked TLG [3,16,[19][20][21]. The hybridized bands are characterized by a strong trigonal warping. For very strong electric fields, a new set of Dirac points was theoretically predicted, with masses and velocities that are controlled by the electric field [18,22]. Thus biased TLG can potentially provide an opportunity to study chiral carriers with tunable anisotropic dispersion, different symmetry, and higher valley degeneracy (6 as opposed to two in MLG and BLG), not accessible in MLG and BLG.Here we report on transport studies of high-mobility TLG samples in the quantum Hall effect regime. We fabricated dual-gated TLG samples encapsulated in hexagonal boron nitride [23,24] crystals (hBN) [Figs. 1(a)-1(b)], which allowed us to independently control the carrier density n and perpendicular electric displacement field D. We use magnetotransport measurements to study how Landau levels (LLs) evolve under D. By inspecting the pattern of LL crossings resulting from the hybridization of the BLG-like and MLG-like bands as a function of n, D, and magnetic field B, we are able to refine the values of the TLG band structure parameters.Additional...

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“…Subsequent measurements on dual-gated suspended devices by Lee et al 34 observed ν = ±2 plateaus at low magnetic field B < 4 T and also resolved, in high magnetic fields, additional plateaus at ν = ±1, ±3, −4, and −5, indicating almost complete lifting of the 12-fold degeneracy of the LLL. Common to these observations, in particular, is eh asymmetry in the sequence of plateaus, with a prominent ν = −2 plateau.…”

Section: Coulomb Interactionsmentioning

confidence: 82%

Interaction-enhanced electron-hole and valley asymmetries in the lowest Landau level ofABA-stacked trilayer graphene

Shizuya

2014

Phys. Rev. B

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In a magnetic field graphene trilayers support a special multiplet of 12 zero(-energy)-mode Landau levels with a threefold degeneracy in Landau orbitals. A close look is made into such zero-mode levels in ABA-stacked trilayers, with the Coulomb interaction taken into account. It turns out that the zero-mode Landau levels of ABA trilayers are greatly afflicted with electron-hole and valley asymmetries, which come from general hopping parameters and which are enhanced by the Coulomb interaction and the associated vacuum effect, the orbital Lamb shift, that lifts the zeromode degeneracy. These asymmetries substantially affect the way the zero-mode levels evolve, with filling, via Coulomb interactions; and its consequences are discussed in the light of experiments.

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Broken Symmetry Quantum Hall States in Dual-Gated ABA Trilayer Graphene

Cited by 46 publications

References 55 publications

Transport Studies of Dual-Gated ABC and ABA Trilayer Graphene: Band Gap Opening and Band Structure Tuning in Very Large Perpendicular Electric Fields

Transport Studies of Dual-Gated ABC and ABA Trilayer Graphene: Band Gap Opening and Band Structure Tuning in Very Large Perpendicular Electric Fields

Landau Level Splittings, Phase Transitions, and Nonuniform Charge Distribution in Trilayer Graphene

Interaction-enhanced electron-hole and valley asymmetries in the lowest Landau level ofABA-stacked trilayer graphene

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