Recent experiments indicate that AA -stacked bilayer graphenes (BLGs) could exist. Since the energy bands of the AA -stacked BLG are different from both the monolayer and AB -stacked bilayer graphenes, different integer quantum Hall effect in the AA -stacked graphene is expected. We have therefore calculated the quantized Hall conductivity σxy and also longitudinal conductivity σxx of the AA -stacked BLG within the linear-response Kubo formalism. Interestingly, we find that the AA -stacked BLG could exhibit both conventional insulating behavior (the ν̄=0 plateau) and chirality for |μ̄|<t , where ν̄ is the filling factor, μ̄ is the chemical potential, and t is the interlayer hopping energy, in striking contrast to the monolayer graphene and AB -stacked BLG. We also find that for |μ̄|≠[(n2+n1)/(n2-n1)]t , where n1=1,2,3,… , n2=2,3,4,… , and n2>n1 , the Hall conductivity is quantized as σxy=±(4e2)/(h)n,n=0,1,2,… , if |μ̄|<t and σxy=±(4e2)/(h)n,n=1,2,3,… , if |μ̄|>t . However, if |μ̄|=[(n1+n2)/(n2-n1)]t , the ν̄=±4(n1+n2)n plateaus are absent, where n=1,2,3,… Furthermore, we find that when the magnetic field B=πt2/NehυF2 , N=1,2,3,… , the ν̄=0 plateau across μ̄=0 would disappear and the 8e2/h step at μ̄=t would occur. Finally, we show that in the low-disorder and high-magnetic-field regime, σxx→0 , as long as the Fermi level is not close to a Dirac point.
Physical Review B
- Pub Date:
- October 2010
- Theory and modeling;
- Landau levels;
- Condensed Matter - Mesoscale and Nanoscale Physics
- submitted to Physical Review B