Density of states of disordered graphene

Hu, Ben Yu‐Kuang; Hwang, E. H.; Sarma, S. Das

doi:10.1103/physrevb.78.165411

Cited by 78 publications

(87 citation statements)

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“…4,5,6,7,8 However, such a phenomenon as spectrum rearrangement is frequently overlooked. The main concept of the spectrum rearrangement is based on the existence of some critical impurity concentration, at which the spectrum of a disordered system undergoes a cardinal qualitative change.…”

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confidence: 99%

Numerical evidence of spectrum rearrangement in impure graphene

2009

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By means of numerical simulation we confirm that in graphene with point defects a quasigap opens in the vicinity of the resonance state with increasing impurity concentration. We prove that states inside this quasigap cannot longer be described by a wavevector and are strongly localized. We visualize states corresponding to the density of states maxima within the quasigap and show that they are yielded by impurity pair clusters.

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confidence: 99%

Numerical evidence of spectrum rearrangement in impure graphene

2009

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“…Depending on the disorder type and approach, a vanishing, a finite, or an infinite DOS at the Dirac point has been suggested for graphene or related models. 24,25,26,27,28,29,30,31,32,33,34 Also, the interpretation of experimental results is hampered by the uncertainty regarding the precise form of the DOS. Recently, following earlier experimental investigations of the Landau level splitting in high magnetic fields, 35,36 the opening of a spin (Zeeman) gap in the density of states at the Dirac point has been suggested in the interpretation of magneto-transport measurements on graphene sheets.…”

Section: Introductionmentioning

confidence: 99%

Narrow depression in the density of states at the Dirac point in disordered graphene

Schweitzer

2009

Phys. Rev. B

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The electronic properties of non-interacting particles moving on a two-dimensional bricklayer lattice are investigated numerically. In particular, the influence of disorder in form of a spatially varying random magnetic flux is studied. In addition, a strong perpendicular constant magnetic field B is considered. The density of states ρ(E) goes to zero for E → 0 as in the ordered system, but with a much steeper slope. This happens for both cases: at the Dirac point for B = 0 and at the center of the central Landau band for finite B. Close to the Dirac point, the dependence of ρ(E) on the system size, on the disorder strength, and on the constant magnetic flux density is analyzed and fitted to an analytical expression proposed previously in connection with the thermal quantum Hall effect. Additional short-range on-site disorder completely replenishes the indentation in the density of states at the Dirac point.

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“…If the spin-orbit (SO) interaction is neglected [7,8,9, 10], the energy spectrum in these points is degenerate, and the elementary excitations belong to the linear spectrum, which can be described by the two-dimensional relativistic Dirac model [6]. In reality, the SO interaction is not zero and, correspondingly, there is an energy gap [11].…”

Section: Introductionmentioning

confidence: 99%

Discrete and resonance states in graphene near the Dirac point

Inglot

Dugaev

2011

J. Phys.: Conf. Ser.

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Abstract. We consider the problem of impurity states in the vicinity of Dirac point in graphene taking into account the spin-orbit (SO) interaction. Two main contributions to the SO interaction, namely the internal and Rashba, are considered. Even though the internal SO interaction is relatively small, its effect is crucial because a very small perturbation potential can create both discrete and resonance impurity states located near the gap. In the case of strong Rashba SO interaction like in the case of graphene on a substrate, the resonance impurity states can be created producing some anomalies in transport properties. IntroductionElectric and magnetic properties of graphene are mostly determined by the electronic states in the vicinity of Dirac points [1,2,3,4,5]. If the spin-orbit (SO) interaction is neglected [7,8,9, 10], the energy spectrum in these points is degenerate, and the elementary excitations belong to the linear spectrum, which can be described by the two-dimensional relativistic Dirac model [6]. In reality, the SO interaction is not zero and, correspondingly, there is an energy gap [11]. However, it was found that in case of internal SO interaction the magnitude of SO gap is very small, and correspondingly it can be neglected [12,13,14,15]. In this paper we demonstrate that even though the energy gap is really very small, the presence of SO interaction of any origin leads to formation of additional low-energy impurity states, which are absent if the SO interaction is neglected. Besides, we find that the impurity creating very small perturbation like, for example, some neutral adatoms or molecules, can be responsible for these states.In the case of SO interaction related to the Rashba term, the magnitude of SO is not necessarily small, and the energy spectrum at low energies is completely different from the Dirac spectrum. In this case one can also study the problem of impurity states, which can be effectively controlled by electric gate, as it is known that the electric field of the gate modifies the magnitude of Rashba SO coupling.

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Density of states of disordered graphene

Cited by 78 publications

References 50 publications

Numerical evidence of spectrum rearrangement in impure graphene

Numerical evidence of spectrum rearrangement in impure graphene

Narrow depression in the density of states at the Dirac point in disordered graphene

Discrete and resonance states in graphene near the Dirac point

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