Low-Density Ferromagnetism in Biased Bilayer Graphene

Castro, Eduardo V.; Peres, N. M. R.; Stauber, T.; Silva, N. A. P.

doi:10.1103/physrevlett.100.186803

Cited by 140 publications

(112 citation statements)

References 39 publications

(36 reference statements)

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“…[4] are fully consistent with the properties of the bare anisotropies u (0) ⊥,z (B ⊥ ), whereas the deviation from linearity at lower B ⊥ 2T can be explained by enhanced renormalizations of u ⊥,z (B ⊥ ) as the transition to the low-magnetic-field interaction-induced state of debated nature [28][29][30][31][32] is approached.…”

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confidence: 59%

Canted Antiferromagnetic Phase of theν=0Quantum Hall State in Bilayer Graphene

2012

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Motivated to understand the nature of the strongly insulating ν = 0 quantum Hall state in bilayer graphene, we develop the theory of the state in the framework of quantum Hall ferromagnetism. The generic phase diagram, obtained in the presence of the isospin anisotropy, perpendicular electric field, and Zeeman effect, consists of the spin-polarized ferromagnetic (F), canted antiferromagnetic (CAF), and partially (PLP) and fully (FLP) layer-polarized phases. We address the edge transport properties of the phases. Comparing our findings with the recent data on suspended dual-gated devices, we conclude that the insulating ν = 0 state realized in bilayer graphene at lower electric field is the CAF phase. We also predict a continuous and a sharp insulator-metal phase transition upon tilting the magnetic field from the insulating CAF and FLP phases, respectively, to the F phase with metallic edge conductance 2e 2 /h, which could be within the reach of available fields and could allow one to identify and distinguish the phases experimentally. -is well-established [8][9][10][11][12][13][14][15][16][17], it is unambiguously identifying the particular order of the ν = 0 QHFM that presents a challenge. Given the rich phase diagram of the ν = 0 QHFM in MLG [10-13] (and as we show here, in BLG) and the fact that all phases but the spin-polarized one [18,19] are expected to be fully insulating [11,20,21], achieving this goal requires a more detailed both theoretical and experimental analysis.

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confidence: 59%

Canted Antiferromagnetic Phase of theν=0Quantum Hall State in Bilayer Graphene

2012

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“…34,35 In the presence of a perpendicular magnetic field, the biased BLG shows cyclotron mass renormalization and an extra plateau at zero Hall conductivity, signaling the presence of a sizable gap at the neutrality point. 10,12,36 Gaps can also be induced in stacks with more than two layers as long as the stacking order is of the rhombohedral-type, 11,14 although screening effects may become important in doped systems with increasing number of layers.…”

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confidence: 99%

Electronic properties of a biased graphene bilayer

Castro

Новоселов

Морозов

et al. 2010

J. Phys.: Condens. Matter

301

235

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We study, within the tight-binding approximation, the electronic properties of a graphene bilayer in the presence of an external electric field applied perpendicular to the system -biased bilayer. The effect of the perpendicular electric field is included through a parallel plate capacitor model, with screening correction at the Hartree level. The full tight-binding description is compared with its 4-band and 2-band continuum approximations, and the 4-band model is shown to be always a suitable approximation for the conditions realized in experiments. The model is applied to real biased bilayer devices, either made out of SiC or exfoliated graphene, and good agreement with experimental results is found, indicating that the model is capturing the key ingredients, and that a finite gap is effectively being controlled externally. Analysis of experimental results regarding the electrical noise and cyclotron resonance further suggests that the model can be seen as a good starting point to understand the electronic properties of graphene bilayer. Also, we study the effect of electron-hole asymmetry terms, as the second-nearest-neighbor hopping energies t ′ (in-plane) and γ4 (inter-layer), and the on-site energy ∆.

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“…As a consequence, an isolated (half filled) bilayer graphene would have (4 + δn)/2 electrons per unit cell on B layer (electron-like carriers) and (4 − δn)/2 electrons per unit cell on A layer (hole-like carriers). 45 The second highest valence band of B layer and the second lowest conduction band of A layer are nearly independent on electric fields because they are far away from the Fermi level. In addition, the transferred electrons linearly increase with the electric fields, resulting in the increase of E k g .…”

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confidence: 99%

Intra- and inter-layer charge redistribution in biased bilayer graphene

et al. 2016

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We investigate the spatial redistribution of the electron density in bilayer graphene in the presence of an interlayer bias within density functional theory. It is found that the interlayer charge redistribution is inhomogeneous between the upper and bottom layers and the transferred charge from the upper layer to the bottom layer linearly increases with the external voltage which further makes the gap at K point linearly increase. However, the band gap will saturate to 0.29 eV in the strong-field regime, but it displays a linear field dependence at the weak-field limit. Due to the AB-stacked way, two carbon atoms per unit cell in the same layer are different and there is also a charge transfer between them, making the widths of π valence bands reduced. In the bottom layer, the charge transfers from the direct atoms which directly face another carbon atom to the indirect atoms facing the center of the hexagon on the opposite layer, while the charge transfers from the indirect atoms to the direct atoms in the upper layer. Furthermore, there is a diploe between the upper and bottom layers which results in the reduction of the interlayer hopping interaction.

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Low-Density Ferromagnetism in Biased Bilayer Graphene

Cited by 140 publications

References 39 publications

Canted Antiferromagnetic Phase of theν=0Quantum Hall State in Bilayer Graphene

Canted Antiferromagnetic Phase of theν=0Quantum Hall State in Bilayer Graphene

Electronic properties of a biased graphene bilayer

Intra- and inter-layer charge redistribution in biased bilayer graphene

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