Disorder-driven splitting of the conductance peak at the Dirac point in graphene

Article

关键词: QUANTUM HALL SYSTEMS;    MAGNETIC-FIELD;    ANDERSON MODEL;    LANDAU-LEVEL;    RANDOM FLUX;    LOCALIZATION;    FERMIONS;    DIMENSIONS;    STATES;    PHASE;   

DOI  :  10.1103/PhysRevB.78.205419

来源: SCIE

【 摘 要 】

The electronic properties of a bricklayer model, which shares the same topology as the hexagonal lattice of graphene, are investigated numerically. We study the influence of random magnetic-field disorder in addition to a strong perpendicular magnetic field. We found a disorder-driven splitting of the longitudinal conductance peak within the narrow lowest Landau band near the Dirac point. The energy splitting follows a relation which is proportional to the square root of the magnetic field and linear in the disorder strength. We calculate the scale invariant peaks of the two-terminal conductance and obtain the critical exponents as well as the multifractal properties of the chiral and quantum Hall states. We found approximate values nu approximate to 2.5 for the quantum Hall states but nu=0.33 +/- 0.1 for the divergence of the correlation length of the chiral state at E=0 in the presence of a strong magnetic field. Within the central n=0 Landau band, the multifractal properties of both the chiral and the split quantum Hall states are the same, showing a parabolic f[alpha(s)] distribution with alpha(0)=2.27 +/- 0.02. In the absence of the constant magnetic field, the chiral critical state is determined by alpha(0)=2.14 +/- 0.02.

【 授权许可】

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